Just discovered this thread again and realized I didn't answer yet. Sorry about that.
Did you solve your problem?
If not, here is a possible solution:
(Prerequisite is, that each player sprite has an instance variable with the players Multiplayer ID. You could set this "on connected" or when the sprite is created)
- If the host gets the info that a player starts walking, he needs to get that player's ID with the message (Multiplayer.FromID).
- The host then sends out a message with the tag being "walk" for example to all peers with the content being "playerID=[...]".
- The peers, on receiving a message with the tag "walk", will set the player's sprite to the walk animation.
(it picks the correct sprite by evaluating the received PlayerID and picking the corresponding sprite that has the same PlayerID as its instance variable)
This may sound like much, and I have the feeling that I didn't explain very well (I'm about to go to sleep), so if you need more explaining, just give a shout.
(And if you already solved it, I'd be interested in how your solution looks like)