Naughty Boy.

A stingy uncle is taught a lesson when he is tricked into adopting a grown man instead of a ten-year-old kid. When aspiring poet Karl King is engaged to ballerina Mimi, he falls into disfavour with his benefactor: his uncle. The uncle threatens to adopt an orphan boy as an heir instead. However, in a comic plot, King’s adult brother-in-law takes on the role of a ten-year-old adopted son and displays his most mischievous side! (Stumfilm.dk)