FirstLoveMovies

.Mother and son, Trinidad (42) and Camilo (21) must rent a room in an old house in southern Chile to be able to financially support themselves after the abandonment of the father of the family. In the privacy of this small room, living between solitude and nature, their relationship will be transformed. A mother and her child, united by a common guilt of conscience.
—cinechile

A film does not have to be primarily about children and they don't need to be the central characters, but they must be more than mere 'props'. In other words, if the children in a film could be removed without changing the plot or they're only shown for a minute or two, the movie probably isn't FLM material. In general, kids should have at least 10% screen-time.

'Children' includes kids up to the age of 16. Many children's roles are played by actors or actresses older than that, but if the characters they play are 16 or younger, that's acceptable.