if you are ready for level-2 macros... those using focus for the first time... then try something like this:

each wow would have these macros (pick your own keys):
f1: /focus joe
f2: /focus sam
f3: /focus bob

when joe dies, hit f2 and sam becomes the new 'main'. which is useful as your powers are defined like this:

1: /startattack [target=focustarget]
2. /cast [target=focustarget] fireball
-: /assist focus
=: /follow focus

you only need to set your focus once until that character dies... or your main comes back...

if you want to get tricky... and you're using keyclone's maximizer... set your PiP hotkey to match the /focus keys
if you do it right, hitting a single key, ie: f2, sam will swap with joe... and sam will become focus