I think mod teams should handle anything one of their affilitiates explicitly creates for their mod in his stead - via their readme - and that it should be subject to their respective license (which should be included in said readme).

Also, modders should be made aware then that by joining the mod team the rights to any work they do for the mod will go to the team and not stay with the person - unless the team (or a responsible representative) explicitly agrees to make an exception.

I think we should generally work on those license modes (maybe I'll write a few paragraphs when I'm up to using that kind of language ;)) and maybe we can even establish a few standards that can just be copied (Creative Commons like).
Maybe one of the more experienced modders should also create a tutorial on this to show newbies how we'd like it to be done :)

I'll also release the Chivalry readme as an example if you consider it as a good one (after I wrote it of course).