VectorMusic
Yeah that's a good idea. So there are multiple ways to ensure a solid connection to the parent and your interventional approach is one of the ways for sure. I guess the only other way is to adopt the tone and writing style of the movie The Dry. Obviously since it isn't a text-based media, when I say "writing style", I mean how the directors have scripted the dialogue between characters and how the background sounds (diegetic and non-diegetic) play into the overall tone and message of the movie. So, for example and from a brief scan of The Dry, you could maintain the similar rural Australian town with the same oppressive atmosphere and tension. The recurring themes of drought, isolation, etc. could be central.
So in summary, if you're worried, the recommendation would probably be doing an interventional writing which is what you're doing. So in doing this, I've seen people write a story that focuses into the backstory of a secondary character or expand on a certain event that was only hinted or foreshadowed at in the movie.
Anyways, hope it helps!