But how would you know? If only one Wikileaks donation makes it into the final txn, wouldn't each participant just assume it was their donation? How could they tell otherwise?
Reference the original offers in the join request, so that anyone considering signing the transaction can make sure that not just the correct outputs, but also the correct number of outputs are present. My Python implementation does this.
Can you link to your implementation, please? I'd like to have a look because I don't fully understand.