Most people seem to have macro's set up as one of these:

target = focus
target = party1
or the FTL system

In all of these, the toon to be assisted is easily found.
And that toon targets whatever we want our slaves to end up targeting.

I'm not sure why someone would have a heal and word it:
/target [target=party3] Rejuvenation

When they could word it just as easily:
/target [target=Toon'sName] Rejuvention