pawpaw flowers are like most annona flowers, protogynous...meaning each flower is female, then turning male. So you really only need one pawpaw for fruits...although u might need to hand pollinate...and some are more self fruitful than others....and cross pollination would probably help increase fruit set, but not absolutely necessary to get fruits.
BTW...I've traded with Charles (Rarefruit) many times, and he is one of my favorite person's to deal with!