If you have Jamba, your slaves should mimic the master/active toon, for gossip options, provided the window is open on all toons.

Basically have your slaves assist the leader (via the Mapped Key: FTL Assist Me), and then Interact With Target, until each of the characters has the same window open on the NPC.

Then do whatever, and have Jamba mimic the action.

Alternatively, once the window is open, enable Repeater (or Mouse Repeater, if you broke Repeater into two mapped keys - Mouse Repeater and Keyboard Repeater). That way, anything you click on one, will be clicked on both at once.