I'm not sure but I'm telling what I remember..

Uhm I think they were parents... they were aliens. Its was sure a comedy science fiction movie... the kids didn't know they were aliens.

The father was fat had blue/flower shirt. a crème short pence and glasses.
And the mother was / I think pink kitchen clothes en red hair. The movie picture
Was yellow at background. and they all were looking up. Of early 90"s

At the end they were on the roof... they were not famous actors.
I only remember the fat guy really good. Just want to see it back.