A share waypoint button and the formatted text feature is missing in the 1.7.10 version of journeymap.
This simple mod adds those features and some other quality of life improvements.
https://www.curseforge.com/minecraft/mc-mods/journeymap
New commands: cleardeath, share, remove
If you type or receive correctly formatted text, it is converted into a waypoint that is automatically "clicked" or added to your waypoints list.
You can disable the auto click feature with the command and manually click on waypoints in chat.
The ApiWaypointManager class has some functions that handle the packets for sharing and removing waypoints.
This command only works on the client side. Doesn't work on command blocks or custom npcs. See /wpcreate
/waypoint share <waypoint name> [player_name/@a/@p]
/waypoint cleardeath [number of recent death points to save]
/waypoint remove <waypoint name>
/waypoint removeprefix <prefix name>
/waypoint disableautoclick (true/false)
This command works on both server and client side. It can be used to create waypoints with command blocks. See Formatted Text for a description of each parameter.
/wpcreate <@s/@a/@p/@t:team_name/player_name> <name> <x> <y> <z> [color] [dim] [delete]
A waypoint in chat must be enclosed by square brackets. Parameters are split by "," and defining a parameter uses ":"
x (integer | x coordinate | required)
y (integer | y coordinate | 60)
z (integer | z coordinate | required)
dim (integer | dimension number | 0)
name (string | waypoint name | x and z coordinate)
color (hexadecimal integer | waypoint color | #FFFF00)
delete (boolean | delete all other waypoints with same name | false)
[x:105,y:72,z:-723,dim:0,name:Test,color:#B311CF,delete:false]
https://www.curseforge.com/minecraft/mc-mods/journeymap-waypoint-radar