Hello, i use this makro and it works:
Code:
/focus [target=Maincharname,nodead][target=Toon1,nodead][target=Toon2,nodead][target=Toon3,nodead][target=Toon4,nodead][target=Maincharname,exists][target=player]
/assist focus
/cast Spellname

(replace the fat printet variables with your characternames)
if you want that your toons following the mainchar (or the focustarget) use /follow focus

If your regular mainchar dies, switch to the next wow window with your mouse an the show goes on )
The makro will set your next toon who is sill alive as the focustarget and the other toons will now assist him.

(sorry for my bad english but i hope i could help you)