
Well the stud owner will ahve to sign the litter registration foirm, so the only way to cheat the sires owner would be if a litter were born and not registered, whcioh would rather defeat the object.
Most stud owners will sign the form wehn they ahve been paid, in the case of a puppy as fee they may have to take it on trust as pups would nortmally be registered before homing, but if they didn't trust you that far you might have to register teh pusp later and give the new pups owners leters telling them the KC reg would follow. Another way would be simply to pay the stud fee, at mating, and then the stud owner could buy the puppy they wanted from you.