You probably know more about macros than I do so I'm not sure how much help I'll be. Isn't there a /targetexact type command? That could help with the /follow issue.

Also, I like your plan for a different reason: different groups compositions. Using a typical FTL makes it very tough to sub one toon in on account A for another toon on account A. Using your system I can easily expand it a little bit so that the chain of /assist also takes into account modifiers so that all I need to do is load a new HKN script that passes a modifier (such as ctrl) with each broadcasted keystroke.

In other words, if my group is sometimes:

Account 1 -> Pally Tank
Account 2 -> Moonkin1
Account 3 -> Moonkin2
Account 4 -> Moonkin3
Account 5 -> Shaman Healer

and instead I want to try other toons I have on my account, such as:

Account 1 -> Moonkin4
Account 2 -> Moonkin1
Account 3 -> Moonkin2
Account 4 -> Moonkin3
Account 5 -> Shaman Healer

I could just have my macros do something like the following:

Code:
/assist [target=Moonkin2]
/assist [target=Moonkin1]
/assist [target=Pally Tank, nodead, nomod:ctrl],[target=Moonkin4, nodead, mod:ctrl]
/cast Lightning Bolt