I had a rez macro, similar to yours...
But instead of party1, party2 etc, it was toon names.
And it broke a few patches back.

Something like:
/cast [dead][dead,target=ToonA][dead,target=ToonB] Rez Spell

Using party #'s is a good idea.
Ideally, in the case of multiple toons down, I'd like both to be rez'd on the one click.
Could accomplish that, by a fixed invite order, and party #'s.