This is going to be quite vague, but back in the 90’s, I read a series 4 books about 4 sisters. Each book was named after 1 of the sisters and that book particularly focused on that sister. I think they were set in the 1920’s - 1940’s but i’m not completely sure.
I have no idea of the author or even the titles. I’ve googled them many times over the years and never found them, probably because my description is so vague! Do they sound familiar to anyone?