I use to watch a movie in elementary school about a brother and sister who enter a colouring book. They meet this lady in white and she is sad because all the families of colours are fighting and she needs them all to get along so she gets her colour back. They visite all the families one by one and sing children songs.

Wee Sing in Sillyville (1989)

Haha funny how that works isn't it? I have never seen The Hugga Bunch Movie, but I can tell you the plot exactly, and pick it out right away from the vaguest of descriptions.