Uh, since the username is followed with avatar of player, so you might add a private variable "name" in sprite of player, then assign this variable when created by sync-command.
The sync-command is just like a chatting message in mini-town, the different is, you need to design the parameters for sprite creating.
Add "name" in sync-parameter like "x" or "y",
<img src="http://i1081.photobucket.com/albums/j352/rexrainbow1/Sync-command.png" border="0" />
Push parameters into sync-command, then all clients will get them.