You say you want a pup from the bitch, well why? If its because she has proven herself as a worker then let her have this litter. If not, then why do you say you want a pup from her?
accidental mating maybe not the the dog he wants an as said when his own bitch start slowing down then he'll pup her space bein another possible reason like myself I've to bitches I'd like to cover an like him want to keep one of each cut sure I've no space so until then no breeding