what about collective creations, when more than one person creates the same artwork? this should be ok, right?
I don't really see any issues here.
As long as the artwork is original and is composed or conceptualize by you and your colleagues -- that's fine. However, you will be the one responsible distributing the rewards among your friends since they are involved who put an effort in making the artwork materialize.
Just don't commit plagiarism/artwork stealing -- there is nothing to worry about. Goodluck.
of course, collaborators will have to trust the receiver of the prize so they don't get stolen but should be fine with friends and honest people