The Silence - Ingmar Bergman

"The Silence" is about the emotional distance between two sisters. The younger one is still attractive enough to pick up a lover in a strange city. The older one -- even though she is very ill -- would like to make a human connection also but cannot leave the hotel room. Traveling with the sisters is a small boy who escapes into the hotel, meets a troupe of dwarfs. Which sister is this little boy's mother?