All show puppies need to go on a contract that will not allow breeding unless the dog lives up to the quality intended and passes all health checks and certification necessary for that breed. Co-ownerships allow you a certain amount of control in this regard because they require your signature in order that puppies be registered. The latest news from the AKC is that there is a pending change to the rules that will not allow registration unless all papers are properly signed. If you have a difference with your co-owner it will need to be settled in court before the AKC will register litters or puppies. This is new and still pending, but a step in the right direction.
Every breeder owes to the breed and to themselves to be involved with rescue.
Every breeder should be prepared to take any dog back for whatever reason. If they do not have the space, then they need to be prepared to make other arrangements. In my ideal world one could not sell dogs. They would only be able to be given as cherished gifts to deserving individuals. This would eliminate the whole pet mill and back-yard breeding industry as they could not make any money.