[vegbunny83]

If your parents really refuse to brush the dogs' teeth, have you considered paying for yearly dental cleanings for the dogs and having your parents buy enzymatic chews/rinses from the vet? The enzymatic products aren't as effective as brushing the dogs' teeth (in my opinion) but they will provide some protection against calculus buildup if given regularly. Also, maybe at least get them to put some of the doggy toothpaste on a treat and give it to the dogs once a day. If it is the enzymatic toothpaste, the enzyme action will help clean their teeth, and it's not as time-consuming as brushing.

Also, perhaps pay for the dogs to go to a professional groomer once a month so their coats stay nice. The doggy daycare/dog walker idea is good as well.