Subsribing Selected Users to Collections

I’m working on a chatroom/social network type site: based on Zenva Tutorial and recently added a few channels (without iron:router) to help disperse the flow of traffic. Now I would like to take it a step further in allowing users to create channels only with selected other users. I imagine I would do this through something akin to a form, which asks for channel name and which users to include, but from then I’m absolutely clueless as to what to do, I understand it would involve .subscribe, and a part of the user collection, such as in mine: Username. I’m not basic at meteor but have never gone to anything similar to this.

Any Help is apppreciated,