Training is the best option but if you can't get them there, try this. It's a matter of patience and understanding your dog. If your dog has some obedience training to start, then have them sit when the kids first come over. It's best to keep them on a lease so no accidents happen. Ask the kids to enter the house quietly and sit down. You might even try putting something you wear over the kids laps, so doggie smells you on the kids. Give the kids some dog treats and take the dogs to the children. Have the kids put out their hands, flat with a treat. If doggies learn that the kids are a source of goodies they might come to accept them as family. Never leave the children alone with the dogs. And remind the kids not to pull ears or tails and to have good manners around the dogs.