[Help] My parents have had a dog for 6 years- they just discovered a microchip.

Six years ago, I found a dog in a not-so-great neighborhood. He was sweet and fluffy, no collar, and we immediately became friends. I'm not one to take dogs to shelters, and I had to go out of town for work, so my parents took him. We put up tons of Craigslist posts and flyers, with no luck. Somehow we didn't even think to check for a chip- back then, chips weren't as prevalent. Parents even took him to the vet, told them he was a stray, and they didn't check either. Of course, my parents fell in love.6 years later, today, my dad decided to microchip him, just in case. And it turns out... He's already got a chip.I personally think the right thing to do is notify the owners to let them know he's in a happy place (not hit by a car), but my parents love him SO MUCH, and they're terrified the owners will want him back. He was only about 6 months when we found him, and my parents have had him for 6 years. Obviously we wouldn't offer to give him back, but if the owners wanted to see him again, and happen to fall in love, legally, my parents lose him. And it would break their hearts. We can't just anonymously contact them, we'd have to go through HomeAgain (chip company), so it would immediately become a legal thing. If they so happen to be not-so-nice people, and want him back, there's nothing my parents would be able to do.I know what the "right" thing to do is, but my parents love him so much they're prepared to live with doing the "wrong" thing.Help, Reddit. What should we do?tl;dr: Parents found out their dog has a microchip after 6 years of caring for him. Do we let the original owners know? via /r/dogs http://ift.tt/2qLFU2C