Having team-members split the grade among them by their personal contribution
A problem I see here is that this scheme may motivate people to divide the points &quot;tactically&quot;. Say our group project is worth 10 points and I only need 5 for my goal (which may be the least passing grade or the best grade or whatever). Then of course I would take only 5 points and give 15 to my collegue (which is more than the project is worth).
Also, it might motivate people to look for their partners tactically: If I am somebody who does not trust other people and wants to do everything themselves (something which should ideally be discouraged in group projects), I choose the person who cares least about their grades as a partner and get much more points than my project is worth.
Moreover, with this setting, you treat the grades as some currency. students will find it okay to do less/more work because they can themselves discuss and haggle about the grade they got. IMO this is also not something which should be encouraged.