Looking for suggestions

Has she read the books of Mary Wesley? While not a family saga , they are all interlinked. Maybe she would like Joanna Trollope as well?
If you are on Facebook, join the group First Edition. The readers there will give you lots of ideas.

Yes, I was going to suggest Cynthia Harrod-Eagles as well, but her Morland Dynasty series. It follows a family from the time of the Wars of the Roses to the 1930s. It is certainly well-written, and surprisingly gripping (I don't normally care much for historical novels) and you really want to know what happens next. There are 35 books, so it will keep her going for a while!

Am currently hooked on Cynthia-Harrod Eagles, the Family at War series, though I think she has written loads of others.

Catherine cookson has written lots of books so should keep her going for a while!

Thank you for those suggestions. I will pass them on.

Presumably she’s read Gone with the Wind and the Forsyte saga series?

Might she enjoy Rosamunde Pilcher’s books, Shell Seekers, Winter Solstice, Coming Home, etc?

I think ‘The Building of Jalna’ and that series written by Mazo de La Roche might fit the bill. I remember reading it as a teenager and enjoying it.