I might have a connection with your Robert
Anderson. I'm a direct decendant of the Robert
Anderson that founded the town of
Anderson,
Missouri. He did have a daughter named Mary, but I think she died when she was young. She's no longer listed with the family after 1860 in the US census. But there is a family that gets confused with the Andersons who founded
Anderson, where there's Robert and
Hester Anderson. They may be the one's you're looking for.
However I am connected to the
Meadors through my great-great grandmother
Illinois Meador, who married Robert Anderson's some Stephen
Wilson. Illinois was the sister of your Marshall.
Hope this helps!