can make a hotkey on every character that occupies the same hotkey slot with their respective epic commands.
/useitem "Name of epic"
then on the driver toon make a social to
/bcga /
/keypress HotKeyNumber
Like,
/bcga /
/keypress 9
Then you hit the key on the driving toon and the others will follow, so long as they're not currently casting/moving (assuming cast time requires you stationary)