80s-90s movie with boy and girl walking on roof

I saw this movie around 1991-92 on TV, I do not think it was a TV show. All I remember was seeing a young boy and girl, I think the boy had brownish straight hair, the girl perhaps blondish brown, walking on the top of an uneven rooftop. The girl was more upset than the boy was. I do not think the children were siblings. I remember the father going up one step of stairs, the mother another, maybe the house was a duplex. I think the mother was played by Cynthia Nixon from Sex in the City, but I was a kid when I watched this. I also remember a grocery shopping scene. Does this seem familiar to anyone? Any help would truly be appreciated, thank you.