As a child in the late70's/early 80's, I saw this movie on a pay channel (HBO, Showtime, etc.). These two kids, a girl & boy, are left alone. I think they were orphaned or neglected in some way. I don't remember many details but I do remember the boy made a ham sandwich and poured granulated sugar on it before eating it. It was so weird. What was the name of it?

I also remember that they live in museum or at the mall and come out at night when it closes. The boy takes coins from the fountain and his sister yells at him.

Pretty sure this is From the Mixed-Up Files of Mrs. Basil E. Frankweiler from 1973, based on the children's book. There's also a TV movie from 1995.

Omg! I was just about to ask about this movie, because I thought it was the secret files or the mixed-up files of Mrs. Mumford lol thanks for the help without evening know lol