Changing the group during the game to be able use their group channel?

[Rafalski 10]

MULTIPLAYER

example:

There are several groups, they use GROUP CHANNEL to communicate VON inside the groups, and in one of the groups stays just one soldier, he wants to join another group and be able speak in their GROUP CHANNEL.

Of course he can use Direct channel or side channel but this is not the case.

Unless I don't know how to do it.