Questions about the characters

I'm about halfway into this book, and I actually like it, compared to some other classics I've been reading. I've had to annotate it for english class, so I actually understand most of it.

We're reading this book in a reading group, so we get together once a week and discuss it. I'm in charge of characters...

I've been pretty good about all the characters (I've made an almost complete family tree of the characters), but I'm having a bit of problems. Well, one problem really: Medora Manson.

Who is she? I know she is Ellen's aunt, but how? I really dont' understasnd how she is related to the Manson family, and Catherine Manson Mingott, or if she is at all.

Any clarification about this would be excellent.

Thanks!

Leafy