Something like character list

Let's say that, for example, I want the character I'm going to make to have a friend who also has powers and is already at SA, but don't want him to be an NPC I will control. I post him in this 'list' and if somebody on the site finds him interesting, that member makes him a fully developed character, or simply 'borrows' him to play with me while I need him. Or, for example, you want your character to have a family member visit them at SA but don't want to write them yourself, by yourself. You post a family member you need, I take it, and either play out the scene you need with you so you don't have to write everything yourself, or if I like the character, borrow your idea as a character I can play. It depends on what you/we/everybody agrees on...

I don't know if I'm making myself clear enough, but I don't know how else to explain it.