I don't use focus macros, like to keep my focus free for other stuff. I am using Bartender, and I have a single button on my bars set as my "who to target" button. In each of my spell cast macros, I have the line:

/click BT4Button45Secure
/cast [target=targettarget,harm][] spellname

The macro I have at button 45 is:

/target [target=person1,nodead,help];[target=person2,nodead,help];... etc to person5

My follow macro just consists of

/click BT4Button45Secure
/follow



You can also do this with Trinity Bars and probably other bar mods. It works out great, you put the target button in your alts personal macros and thats the only place you have to change for new alts (I just log in all of em, set it up on one, and then cut & paste it across all screens into new macros).

Sorry, I have no idea how to do it with other bar mods or default Blizzard UI, and even in Bartender finding the button numbers is a pain (I set keybindings to the first button of every bar, then looked in my WTF/bindings-cache.wtf file which tells you the name/keybinding).

Good luck!