Its extremely early in the morning and I can only think of one thing at the moment but it would require more effort than most solutions I think.

You'd have to make two of each macro one for each healer

one with /cast [target=focus] Spell
and one with /cast [target=focus, actionbar:1] [target=target, actionbar2] Spell

this of course means you'd have to use both actionbars however which makes it a less ... "good" solution :P