I got this idea. If I'm working with someone or something, and I post something that includes the two of us, why couldn't he modify the post. For example, currently, I'm working with Twilight Alchemist and Malefor in Shadow of Termina, and as many of you know, we have our sprite topic. This is the point: we are all working with that. And what if I could modify the OP to add MY sprite? That would be way easier for us to put sprites that are finished, and we have it there, as if they are official. Though, this is an example, it would serve to give you the idea. When creating the topic, there should be an option that says "Modified by", and as options "me", so just you can modify your topic, or the "add user" option, in which you add an user, and both can modify the topic.