ive never done a breeding loan, but from what i understand the person doing more of the work gets more of the reward. If you're the one with the females, you should get more since you have to document the breedings, keep track of the females, and then the clutches, incubate the clutches, etc.
Draw up a contract with EVERYTHING. what if your animal gets sick, what if one of his dies/gets lose/is bitten by a rodent/etc. Who gets first pick. What if neither of the clutches are good? what if neither female lays, etc. There is a lot to think about. You should go through an itemized list of what may hatch and then go through it from there. If you want a male pastel het pied (and one hatches) and he has no use for it, that should probably be one of the animals you take, etc.