Villains in Addams Family movies go to really unnecessary lengths to defraud them of the family fortune. These people just give it away on whims all the time. If I just walked into the house and started wearing their clothes and spending their money, they wold start introducing me as Cousin Intruder and forget there was ever a time I didn’t live with them.
There’s a whole plotline in the Addams Family Musical where Morticia and Gomez realize at the same time they each thought Grandmama was the other one’s parent and no one knows who the hell she is, and literally nothing changes because, well, she’s Grandmama now.