@Fizzler

its working for me, but i had some problems with it myself, and i will change some stuff on that function i a couple of days, so try a later version. as i can say, Multiboxer sends the warning to the default raidwarning channel. so i guess some raid addon / move anything addon changed something?

@razorbax

1. WoW Restrictes macros and spells are only could cast by a button press.
2. Macros could be edited by Addons, but only if you out of Combat.

So i think your feature request is PVE only, because Restriction 2. make it very hard to do dynamic macro changing because you 90% in combat while doing PvP.
Ok i understand you problem like this:
If you use party1...4 for your healmacros you always have to relearn which user is which on the healer slave, if you use Playernames you are able to heal your master and slaves, but you cant heal your guild/pug members.

So as you can't trigger because of restriction 1 you slave to heal playerX you have to alter the macros on the slave. the easiest way could be you have one heal button and 4 dynamic target buttons. the 4 targeting buttons are bound to a macro which will be created/altered by an addon.
Another way is that the Master stores some kind of macro library for the slaves and you could use an update macros on slaves button.

I think its could be possible to create a addon or feature to multiboxer which allows the master to create the macro templates (i think the macro completly but with a special TAG in it which will be replaced with the playername of the masters playerorder)
I will doing some testing this week and hope i could add a feature like that in the future.

smurfy