[MUTEant]

I'm not yet very good at macros with conditions but something like that:

/cast [target=focustarget,exists] spell1, [target=focus,noexists] spell2

should work at any bars.
As I said I would have to dig in macros and try that ingame first as that example will propably not workat all, but I'm almost sure it is possible to make using that sort of macro, maybe just a bit more complicated...