The obligation to feed one's wife is one kind of obligation. To the Rif and most Rishonim it is from the sages, not the Torah. To the Rambam, it is from the Torah. There is also an obligation for a widow to be feed until she remarries. But there is no obligation to give anything to a divorced woman except the Ketubah itself. There is nothing called "Mezonot" "Food". This fact has always bothered me about courts that do not see the difference between divorced women and widows.
In any case, I wanted to introduce the subject of a case where you have a few widows. [I.e. the same husband married them all at different times.]
[Rambam laws of marriage 18 law 14] They all get the ketubah according to the time they were married but mezonot/food they all get at the same time.The Ravvad says the reason is the obligation of the Ketubah is because they were married. The obligation of Mezonot is because he died. So it is like "borrowed and borrowed and then bought" [at the end of Bava Batra] where all get the same.
Rav Shach I see deals with this issue.
