what you want is a little different.

What I currently use is this for healing on my 3 priests:


/cast [target=party1target, help] Greater Heal
/cast [target=target, help] Greater Heal
/cast [target=player] Greater Heal


you can replace party1target with focustarget if you set your main as focus. My main is always leader in the party so i use party1target as party1 is always the leader (except for the leader character himself)

Anyway, this macro will:
- first check for your leaders target, if that target is friendly, it will heal it, if not, it will check for that toon's own target, and if thats friendly, it will get healed, if that toon has no target either or a hostile one, it will heal himself