One way you could possible do this is by, when Rapunzel is remembering her child hood, so her parents. as in the movie she has a flashback but instead of a flashback you could turn it into a dream sequence. you could also make another dream sequence about flin rider. as you probably know, Rapunzel has a crush on him, most likely making her think more about him, or dreaming about him. this one you could also make it humors, since we all know flint is quite a charmer.
hopefully this helps you!