I kind of had that happen when I was growing up with the next-door neighbors.
The house next to us sold to a couple that had kids from other marriages. I befriended the early teen guy; he was just a year younger than me. I was over at their house on a regular basis.
So the elder son of the Dad started hooking up with the older daughter of the Mom. It was halfway expected. They'd been sweet on each other since they were little kids. In a year or so, they got married. I went to the wedding. That was about 50 years ago; when last I looked they were still married.
I have to say it made for some interesting times visiting my friend.
Relatives got some TV work in that one? The one's from up the holler?
Hey now, if that commercial was made today. The boy would be a groid and that chic would be fat with blue cotton candy hair. The parents would be mixed race marriage