Location shots?

I am curious to know whether the Steves Homestead was used for the Mexican Governor's mansion in "The Iron Mistress." I toured the Steves Homestead in the King William historical district of San Antonio in the 1970s, and I immediately recognized it in the film. The drawing room with french doors, in which Teresa is playing the piano, is the room of this mansion that I vividly remember. The piano also is same one or is exactly like the 1800s piano in the home. Of course, sometimes duplicate rooms are built on soundstages, but it would be interesting to know if the actual Steves Homestead was used in the film.