I agree with Chris and Ladyjrnlist. Don't go. Why would you infringe on her Dad's celebration of his art? Why would you put her in an uncomfortable position, particularly on this kind of occasion? She needs to be there for her dad, as his daughter, without any kind of dual role being forced on her. If you want to see his art, then go on another day. I don't think that being her patient gives you the right to "observe" her family. That feels somewhat stalkerish, actually.