Nothing to stop you requesting this info be passed on by the controller, " XXXX, please advise G-XX of Chinook at 11 O'Clock, heading our way" as your other aircraft will be on the frequency anyway they will get the info as soon as you transmit it.
So what if I want to call my partner in crime into right echelon? I can't use hand signals necessarily as he may be in trail and I'd prefer not to use a third party as it can easily cause distraction - and I have yet to hear any formation do that....
We use a quiet frequency where possible. If not, we transmit on whichever ATC frequency we are using. If it's done properly, the leader will transmit briefly. The only reply he will expect to hear is "Two" (apart from the occasional controller who hasn't been paying full attention when the formation checks in and transmits "say again" every time
).
No need for chatter.