Very cute pups. It's nice of you and your mom to try and find them good homes, and to use the money to hopefully spay Nikki.
Are you keeping the pups for three weeks, until they are ready to leave each other? Have you thought about sort of drawing up an adoption contract stating that the pups must be spayed/neutered by 6 months of age? Good luck at finding homes, and at not falling TOO in love with them