I’m thinking along the lines of older spouse dies, younger spouse marries someone younger and becomes the older spouse. Then older spouse dies again and repeat. Has anything like this happened in a long enough chain to be significant? Is it so mundane no one cares?
With ancestry, yeah, that’s going to suck and it’s the bigger database, but with familysearch, you’ve got an API:
https://www.familysearch.org/developers/docs/api/resources
Not sure what your limits are.