@diavolosims , I do not work for EA, but here is my head-cannon: I think they are just 2 roommates who happen to have the same name! Morse is a common enough name for that to happen. (One of my favorite music bands had 3 members with the same last name , but none of them were related! 😅)
I think what really happened is that they meant to give them a relationship , but forgot. That has happened to me more times than I can count! 🤭🤦♀️😅
Alternatively, you can give them your own story. Perhaps they are really mother and son, but Vernon is too embarrassed to admit to still living whith his mom, while Gladys might think not want to admit she has a grown son as it makes her look even older... which she might be doing in order not to scare off the much younger Chuck!
Anyway, I hope you get the true answer.🤞 but in the meantime you can have fun with any of the things I suggested, or you might come up with even better ones! 🙌