I would charge some kind of adoption fee to ensure that whoever is taking them isn't using them for bait for fighting dogs, lab experaments, breeding stock, or just an impulse decision that will be dumped later. Make up a contract stating that these pups will be fixed when they become old enough, proof is required afterwards, and that if at some point they can't keep the puppy it is to be returned to you so that you can find it another home instead of the pup being bounced around from home to home. A good way to keep up with all of the pups actually being spayed/neutered is to use the adoption fee to have it done. They set up the appointment to have it done and you go pay for it. This will prevent any more accidental litters.