diff --git a/src/main/scala/com/fluency03/blockchain/api/actors/BlockchainActor.scala b/src/main/scala/com/fluency03/blockchain/api/actors/BlockchainActor.scala
index 4a6c11f..10c8478 100644
--- a/src/main/scala/com/fluency03/blockchain/api/actors/BlockchainActor.scala
+++ b/src/main/scala/com/fluency03/blockchain/api/actors/BlockchainActor.scala
@@ -1,22 +1,28 @@
 package com.fluency03.blockchain.api.actors
 
 import akka.actor.{ActorSelection, Props}
+import akka.http.scaladsl.server.Directives.onSuccess
+import akka.pattern.ask
 import com.fluency03.blockchain.api.actors.BlockchainActor._
 import com.fluency03.blockchain.api._
 import com.fluency03.blockchain.core.{Block, Blockchain, Transaction}
 
 import scala.collection.mutable
+import scala.concurrent.Future
+import scala.util.{Failure, Success}
 
 object BlockchainActor {
   final case object GetBlockchain
   final case object CreateBlockchain
   final case object DeleteBlockchain
-  final case class GetBlock(hash: String)
+  final case class GetBlockFromChain(hash: String)
   final case class GetTxOfBlock(id: String, hash: String)
   final case class AddBlock(block: Block)
+  final case class AddBlockFromPool(hash: String)
   final case object RemoveBlock
-  final case class MineNextBlock(data: String, trans: Seq[Transaction])
+  final case class MineNextBlock(data: String, ids: Seq[String])
   final case object CheckBlockchainValidity
+  final case class GetBlockFromPool(hash: String)
 
   def props: Props = Props[BlockchainActor]
 }
@@ -25,7 +31,9 @@ class BlockchainActor extends ActorSupport {
   override def preStart(): Unit = log.info("{} started!", this.getClass.getSimpleName)
   override def postStop(): Unit = log.info("{} stopped!", this.getClass.getSimpleName)
 
-  val blockActor: ActorSelection = context.actorSelection(PARENT_UP + BLOCKS_ACTOR_NAME)
+  import context.dispatcher
+
+  val blocksActor: ActorSelection = context.actorSelection(PARENT_UP + BLOCKS_ACTOR_NAME)
   val transActor: ActorSelection = context.actorSelection(PARENT_UP + TRANS_ACTOR_NAME)
   val networkActor: ActorSelection = context.actorSelection(PARENT_UP + NETWORK_ACTOR_NAME)
 
@@ -37,19 +45,20 @@ class BlockchainActor extends ActorSupport {
     case GetBlockchain => onGetBlockchain()
     case CreateBlockchain => onCreateBlockchain()
     case DeleteBlockchain => onDeleteBlockchain()
-    case GetBlock(hash) => onGetBlock(hash)
+    case GetBlockFromChain(hash) => onGetBlockFromChain(hash)
     case GetTxOfBlock(id, hash) => onGetTxOfBlock(id, hash)
     case AddBlock(block) => onAddBlock(block)
+    case AddBlockFromPool(hash) => onAddBlockFromPool(hash)
     case RemoveBlock => onRemoveBlock()
-    case MineNextBlock(data, trans) => onMineNextBlock(data, trans)
+    case MineNextBlock(data, ids) => onMineNextBlock(data, ids)
     case CheckBlockchainValidity => onCheckBlockchainValidity()
+    case GetBlockFromPool(hash) => onGetBlockFromPool(hash)
     case _ => unhandled _
   }
 
   /**
-   * TODO (Chang): new APIS:
-   *  - AddBlock with Block obtained from pool based on hash
-   *  - MineNextBlock with Transactions
+   * TODO (Chang):
+   *
    */
 
   private def onGetBlockchain(): Unit = sender() ! blockchainOpt
@@ -73,10 +82,10 @@ class BlockchainActor extends ActorSupport {
       sender() ! SuccessMsg("Blockchain deleted.")
     } else sender() ! FailureMsg("Blockchain does not exist.")
 
-  private def onGetBlock(hash: String): Unit = sender() ! getBlock(hash)
+  private def onGetBlockFromChain(hash: String): Unit = sender() ! getBlockFromChain(hash)
 
   private def onGetTxOfBlock(id: String, hash: String): Unit = sender() ! {
-    getBlock(hash) match {
+    getBlockFromChain(hash) match {
       case Some(block) => block.transactions.find(_.id == id)
       case None => None
     }
@@ -93,6 +102,25 @@ class BlockchainActor extends ActorSupport {
       sender() ! FailureMsg("Blockchain does not exist.")
   }
 
+  private def onAddBlockFromPool(hash: String): Unit = blockchainOpt match {
+    case Some(blockchain) =>
+      val maybeBlock: Future[Option[Block]] = (blocksActor ? BlocksActor.GetBlock(hash)).mapTo[Option[Block]]
+      maybeBlock onComplete {
+        case Success(blockOpt) => blockOpt match {
+          case Some(block) =>
+            blockchainOpt = Some(blockchain.addBlock(block))
+            hashIndexMapping += (block.hash -> blockchain.length)
+            sender() ! SuccessMsg(s"New Block ${block.hash} added on the chain.")
+          case None => sender() ! FailureMsg(s"Does not find Block $hash in the poll.")
+        }
+        case Failure(t) => sender() ! FailureMsg(s"Cannot get Block $hash from the poll.")
+      }
+    case None =>
+      log.error("Blockchain does not exist! Clear the hash-to-index mapping!")
+      hashIndexMapping.clear()
+      sender() ! FailureMsg("Blockchain does not exist.")
+  }
+
   private def onRemoveBlock(): Unit = blockchainOpt match {
     case Some(blockchain) =>
       val toBeRemoved = blockchain.chain.head
@@ -105,8 +133,17 @@ class BlockchainActor extends ActorSupport {
       sender() ! FailureMsg("Blockchain does not exist.")
   }
 
-  private def onMineNextBlock(data: String, trans: Seq[Transaction]): Unit = blockchainOpt match {
-    case Some(blockchain) => sender() ! Some(blockchain.mineNextBlock(data, trans))
+  private def onMineNextBlock(data: String, ids: Seq[String]): Unit = blockchainOpt match {
+    case Some(blockchain) =>
+      if (ids.isEmpty) sender() ! Some(blockchain.mineNextBlock(data, Seq.empty[Transaction]))
+      else {
+        val maybeTrans: Future[Seq[Transaction]] =
+          (transActor ? TransactionsActor.GetTransactions(ids.toSet)).mapTo[Seq[Transaction]]
+        maybeTrans onComplete {
+          case Success(trans) => sender() ! Some(blockchain.mineNextBlock(data, trans))
+          case Failure(_) => sender() ! None
+        }
+      }
     case None =>
       log.error("Blockchain does not exist! Clear the hash-to-index mapping!")
       hashIndexMapping.clear()
@@ -123,8 +160,10 @@ class BlockchainActor extends ActorSupport {
       sender() ! FailureMsg("Blockchain does not exist.")
   }
 
+  private def onGetBlockFromPool(hash: String): Unit = blocksActor forward BlocksActor.GetBlock(hash)
+
 
-  private def getBlock(hash: String): Option[Block] = hashIndexMapping.get(hash) match {
+  private def getBlockFromChain(hash: String): Option[Block] = hashIndexMapping.get(hash) match {
     case Some(index) => blockchainOpt match {
       case Some(blockchain) => Some(blockchain.chain(index))
       case None =>
diff --git a/src/main/scala/com/fluency03/blockchain/api/routes/BlockRoutes.scala b/src/main/scala/com/fluency03/blockchain/api/routes/BlockRoutes.scala
index c9cd84c..3ac0bd0 100644
--- a/src/main/scala/com/fluency03/blockchain/api/routes/BlockRoutes.scala
+++ b/src/main/scala/com/fluency03/blockchain/api/routes/BlockRoutes.scala
@@ -32,10 +32,11 @@ trait BlockRoutes extends RoutesSupport {
 
   lazy val blockRoutes: Route =
     path(BLOCKS) {
-      parameters( 'hashes.as(CsvSeq[String]) ? ) { hashes =>
-        val blocks: Future[Blocks] =
-          if (hashes.isDefined) (blocksActor ? GetBlocks(hashes.get.toSet)).mapTo[Blocks]
-          else (blocksActor ? GetBlocks).mapTo[Blocks]
+      parameters( 'hashes.as(CsvSeq[String]).? ) { hashesOpt =>
+        val blocks: Future[Blocks] = hashesOpt match {
+          case Some(hashes) => (blocksActor ? GetBlocks(hashes.toSet)).mapTo[Blocks]
+          case None => (blocksActor ? GetBlocks).mapTo[Blocks]
+        }
         complete(blocks)
       }
     } ~
diff --git a/src/main/scala/com/fluency03/blockchain/api/routes/BlockchainRoutes.scala b/src/main/scala/com/fluency03/blockchain/api/routes/BlockchainRoutes.scala
index 02d2ab1..80947c0 100644
--- a/src/main/scala/com/fluency03/blockchain/api/routes/BlockchainRoutes.scala
+++ b/src/main/scala/com/fluency03/blockchain/api/routes/BlockchainRoutes.scala
@@ -7,6 +7,7 @@ import akka.http.scaladsl.server.Directives._
 import akka.http.scaladsl.server.Route
 import akka.http.scaladsl.server.directives.MethodDirectives.{delete, get, post}
 import akka.http.scaladsl.server.directives.RouteDirectives.complete
+import akka.http.scaladsl.unmarshalling.PredefinedFromStringUnmarshallers.CsvSeq
 import akka.pattern.ask
 import com.fluency03.blockchain.api.{FailureMsg, Input, Message}
 import com.fluency03.blockchain.api.actors.BlockchainActor._
@@ -20,9 +21,8 @@ trait BlockchainRoutes extends RoutesSupport {
   def blockchainActor: ActorRef
 
   /**
-   * TODO (Chang): new APIS:
-   *  - AddBlock with Block obtained from pool based on hash
-   *  - MineNextBlock with Transactions
+   * TODO (Chang):
+   *
    */
 
   lazy val blockchainRoutes: Route =
@@ -43,22 +43,27 @@ trait BlockchainRoutes extends RoutesSupport {
           onSuccess(blockchainCreated) { respondOnCreation }
         } ~
         put {
-          parameters('action) {
-            case ADD_BLOCK_ACTION =>
-              entity(as[Block]) { block =>
-                val blockchainUpdated: Future[Message] = (blockchainActor ? AddBlock(block)).mapTo[Message]
-                onSuccess(blockchainUpdated) { respondOnUpdate }
+          parameters('action, 'hash.?, 'id.as(CsvSeq[String]).?) {
+            (action, hashOpt: Option[String], idsOpt: Option[Seq[String]]) => action match {
+              case ADD_BLOCK_ACTION => hashOpt match {
+                case Some(hash) =>
+                  val blockchainUpdated: Future[Message] = (blockchainActor ? AddBlockFromPool(hash)).mapTo[Message]
+                  onSuccess(blockchainUpdated) { respondOnUpdate }
+                case None => entity(as[Block]) { block =>
+                  val blockchainUpdated: Future[Message] = (blockchainActor ? AddBlock(block)).mapTo[Message]
+                  onSuccess(blockchainUpdated) { respondOnUpdate }
+                }
               }
-            case REMOVE_BLOCK_ACTION =>
-              val blockchainUpdated: Future[Message] = (blockchainActor ? RemoveBlock).mapTo[Message]
-              onSuccess(blockchainUpdated) { respondOnUpdate }
-            case MINE_NEXT_BLOCK_ACTION =>
-              entity(as[Input]) { in =>
+              case REMOVE_BLOCK_ACTION =>
+                val blockchainUpdated: Future[Message] = (blockchainActor ? RemoveBlock).mapTo[Message]
+                onSuccess(blockchainUpdated) { respondOnUpdate }
+              case MINE_NEXT_BLOCK_ACTION => entity(as[Input]) { in =>
                 val maybeNextBlock: Future[Option[Block]] =
-                  (blockchainActor ? MineNextBlock(in.content, Seq.empty[Transaction])).mapTo[Option[Block]]
+                  (blockchainActor ? MineNextBlock(in.content, idsOpt.getOrElse(Seq.empty[String]))).mapTo[Option[Block]]
                 rejectEmptyResponse { complete(maybeNextBlock) }
               }
-            case act => complete((StatusCodes.BadRequest, FailureMsg(s"Action Not Supported: $act")))
+              case act => complete((StatusCodes.BadRequest, FailureMsg(s"Action Not Supported: $act")))
+            }
           }
         } ~
         delete {
@@ -69,7 +74,7 @@ trait BlockchainRoutes extends RoutesSupport {
       pathPrefix(BLOCK / Segment) { hash =>
         pathEnd {
           get {
-            val maybeBlock: Future[Option[Block]] = (blockchainActor ? GetBlock(hash)).mapTo[Option[Block]]
+            val maybeBlock: Future[Option[Block]] = (blockchainActor ? GetBlockFromChain(hash)).mapTo[Option[Block]]
             rejectEmptyResponse { complete(maybeBlock) }
           }
         } ~
diff --git a/src/main/scala/com/fluency03/blockchain/api/routes/NetworkRoutes.scala b/src/main/scala/com/fluency03/blockchain/api/routes/NetworkRoutes.scala
index d4f301a..ecc023e 100644
--- a/src/main/scala/com/fluency03/blockchain/api/routes/NetworkRoutes.scala
+++ b/src/main/scala/com/fluency03/blockchain/api/routes/NetworkRoutes.scala
@@ -35,10 +35,11 @@ trait NetworkRoutes extends RoutesSupport {
     } ~
     path(PEERS) {
       get {
-        parameters( 'names.as(CsvSeq[String]) ? ) { names =>
-          val peers: Future[Map[String, Set[String]]] =
-            if (names.isDefined) (networkActor ? GetPeers(names.get.toSet)).mapTo[Map[String, Set[String]]]
-            else (networkActor ? GetPeers).mapTo[Map[String, Set[String]]]
+        parameters( 'names.as(CsvSeq[String]).? ) { namesOpt =>
+          val peers: Future[Map[String, Set[String]]] = namesOpt match {
+            case Some(names) => (networkActor ? GetPeers(names.toSet)).mapTo[Map[String, Set[String]]]
+            case None => (networkActor ? GetPeers).mapTo[Map[String, Set[String]]]
+          }
           complete(peers)
         }
       }
diff --git a/src/main/scala/com/fluency03/blockchain/api/routes/TransactionRoutes.scala b/src/main/scala/com/fluency03/blockchain/api/routes/TransactionRoutes.scala
index 7549899..c29fc56 100644
--- a/src/main/scala/com/fluency03/blockchain/api/routes/TransactionRoutes.scala
+++ b/src/main/scala/com/fluency03/blockchain/api/routes/TransactionRoutes.scala
@@ -30,10 +30,11 @@ trait TransactionRoutes extends RoutesSupport {
 
   lazy val transRoutes: Route =
     path(TRANSACTIONS) {
-      parameters( 'ids.as(CsvSeq[String]) ? ) { ids =>
-        val transactions: Future[Transactions] =
-          if (ids.isDefined) (transActor ? GetTransactions(ids.get.toSet)).mapTo[Transactions]
-          else (transActor ? GetTransactions).mapTo[Transactions]
+      parameters( 'ids.as(CsvSeq[String]).? ) { idsOpt =>
+        val transactions: Future[Transactions] = idsOpt match {
+          case Some(ids) => (transActor ? GetTransactions(ids.toSet)).mapTo[Transactions]
+          case None => (transActor ? GetTransactions).mapTo[Transactions]
+        }
         complete(transactions)
       }
     } ~
diff --git a/src/test/scala/com/fluency03/blockchain/api/actors/BlockchainActorTest.scala b/src/test/scala/com/fluency03/blockchain/api/actors/BlockchainActorTest.scala
index a29bb38..efeacb9 100644
--- a/src/test/scala/com/fluency03/blockchain/api/actors/BlockchainActorTest.scala
+++ b/src/test/scala/com/fluency03/blockchain/api/actors/BlockchainActorTest.scala
@@ -36,11 +36,11 @@ class BlockchainActorTest extends TestKit(ActorSystem("BlockchainActorTest")) wi
       blockchainActor ! GetBlockchain
       val blockchain = expectMsgType[Some[Blockchain]].get
 
-      blockchainActor ! GetBlock("somehash")
+      blockchainActor ! GetBlockFromChain("somehash")
       expectMsg(None)
 
       val genesis = Block.genesisBlock
-      blockchainActor ! GetBlock(genesis.hash)
+      blockchainActor ! GetBlockFromChain(genesis.hash)
       expectMsg(Some(genesis))
 
       blockchainActor ! GetTxOfBlock(genesis.transactions.head.id, genesis.hash)
@@ -67,7 +67,7 @@ class BlockchainActorTest extends TestKit(ActorSystem("BlockchainActorTest")) wi
       blockchainActor ! CheckBlockchainValidity
       expectMsg(SuccessMsg("true"))
 
-      blockchainActor ! MineNextBlock("next", Seq.empty[Transaction])
+      blockchainActor ! MineNextBlock("next", Seq.empty[String])
       val actualBlock = expectMsgType[Some[Block]].get
       actualBlock.data shouldEqual "next"
       actualBlock.transactions shouldEqual Seq.empty[Transaction]
@@ -91,7 +91,7 @@ class BlockchainActorTest extends TestKit(ActorSystem("BlockchainActorTest")) wi
       blockchainActor ! CheckBlockchainValidity
       expectMsg(FailureMsg("Blockchain does not exist."))
 
-      blockchainActor ! MineNextBlock("next", Seq.empty[Transaction])
+      blockchainActor ! MineNextBlock("next", Seq.empty[String])
       expectMsg(None)
 
       blockchainActor ! "other"