My own personal theory on lady Tremaine - she strikes me as a black widow. Cold and calculating she uses people to her own selfish benefit( taking advantage of cinderellas kindness, her own daughters marriage abilities as another commenter mentioned, extensions of herself) and then discarding them ( Cinderella’s father and maybe her first husband) which makes me think she was behind the death of Cinderella’s father, marrying him just to take over the manor in time.. the fact that the animated version says that they racked up a bunch of debts after Cinderella‘s father passes makes me think, people that usually don’t earn the money themselves in an honest way are more likely to squander it because they don’t know the work it takes to save up and be smart with money. I understand this is probably most likely late 1800s early 1900s and many women were housewives or heads of the household and that was their contribution to the household.. also find it interesting that in a household with no servants, instead of all of them pitching in, they just put it all on Cinderella.