We could list a bunch of elements we would like to work with and compose a "skeleton" out of it, then apply it to one of the proposed stories. Assuming our final story would have 3 acts, we could overlap similar elements of interest to team up people. Example:
I wanna make a horror story, about a queer person, solving a mystery.
And then we apply it to one of the stories that were already proposed, like fanfic, so we don't have to worry too much about butchering the original story...