ok - I think i "brute forced" my way through this...

let's say my current toon dies, I hit F7 to switch to a different toon and here's what happens:

1. Maximizer switches views
2. Everyone runs this macro except for the new "main"
/promote Toon2
/focus Toon2
/assist party1
3. The new "main" runs this macro: (also bound to F7)
/clearfocus

This allows me to use focus for my healer, since the focus is updated every time I switch to a new "main" toon.

Since the focus is cleared on the new "main", I can use [target=focus, noexists] as a test for the "main" status in macros, and have separate actions based on main vs slave status - freeing me to use "/assist party1" for targeting as a slave.

I've only VERY roughly tested this... but it seems to work for now.

I'll let you know how testing works out as I use these as I level.

As a bonus, this also cleared a problem I had with the MultiboxerV2 addon where the auto follow was set to "party1" and had the same issue of "remembering" the old party1 after being promoted to leader - I changed option on the auto-follow after combat leader to "focus". Since the new leader has no focus, it doesn't follow anyone