Thanks for the help. This is getting closer, but one thing I can't figure out. Each `scene` is going to have it's own image sequence. I need to run through the sequence before transitioning to the next scene. Playing with your example, after adding any siblings after the one with the image sequence it no longer scrubs through the images.
For simplicity, this fork doesn't actually use anymore image sequences, only more scenes. Don't want to complicate. https://codepen.io/dcha/pen/rNKgbJp