Got this from Hollywood.com:

Nina Van Pallandt

Biography
This striking actress is best known for her roles in the films of Robert Altman. A folk singer who toured Europe with fellow performer Baron Frederik Van Pallandt (to whom she was later married for a period), the Danish-born Van Pallandt made her film debut in Altman's neo-film noir "The Long Goodbye" (1973). She has played leads in a handful of obscure international films and contributed offbeat supporting performances to Paul Schrader's "American Gigolo" (1980) as well as lesser Altman fare such as "Quintet" (1979) and "O.C. and Stiggs" (1987). Van Pallandt earned a degree of notoriety for her romantic involvement with Clifford Irving, whose faked biography of Howard Hughes landed him in prison.

Dunno about Frederik!

LFF