[AmyChristine]

I agree that if you blacken that number then it should be almost impossible for them to see the number to give her full registration. But hopefully you are confident enough in the buyer that that you wouldn't suspect them trying to go out of their way to get full registration to breed a dog that is too small. You could also hold the registration papers altogether until they have proof of spay once you receive conformation of spay you can send them the registration papers. She would still be limited but you would have no reason to worry.