I'm trying to brainstorm better ideas on how to change all characters' focus to my main. Jamba works great with the macro updating, but I don't believe it works in combat.

How do you guys handle it?

To contribute, I'll include the add-ons and macro I use below:
ADD-ONS: Jamba, Hotkeynet

FUNCTION: I use two macros to switch leaders. Each character is setup with a "Make Leader" (CTRL+F) and "Focus Leader" (ALT+F) macro. When I press CTRL+F, HKN broadcasts CTRL+F to my current "Main" window, and ALT+F to my slave windows. Jamba is also setup to make the 'master' character the leader, so the window that initiates /setmeasmaster turns into the group lead. The macros are written as follows:

MAKE LEADER MACRO:
/jamba setmeasmaster all
/clearfocus

FOCUS LEADER:
/focus party1

Since "Party1" is always the group leader, as soon as Jamba makes my "main character" the group lead /focus party1 will always change the slaves focus to the group lead.

The negatives:
1) There's a delay between receiving group lead, so I have to hit the button at least twice for /focus party1 to properly focus on my slave windows
2) If the group lead is someone outside of your Jamba group, then it doesn't work