Who is Marina Veen from Ada; or, Ardor: A Family Chronicle and what is their importance?

Marina is Walter D. Veen's wife. She is an actress who moves between her home in California and Ardis Hall. Marina has two daughter, Ada and Lucette. Ada, howeverm was fathered by her uncle..... not her father. Marina and Dan are life long partners. She dies of natural causes in Nice (France) in 1900.