-- first attempt to target what your main is targeting
/target [target=party1target,exists]
-- next attempt to target anything if you didn't get a target from above for solo casting when needed ( you could be in for a ride if it targets something you don't want )
/targetenemy [noexists]
-- fire away
/cast whatever


just a few suggestions, you may have been wanting to hold a seperate target on each alt for sheep/suduce reasons so this may not work for you.