I'll always remember this one as the game that I played wrong.
As I mentioned in discord, I figured out a couple levels in that you could leapfrog your sister, and then she'd swing around and you could use her momentum to make sick jumps. If she was swinging fast enough, you could get a wall between you and her and abuse that for other big jumps. I didn't even realize you could switch to your sister and extend/retract until I almost beat the game this way. And, to be honest, it was a lot of fun! I hope to see some use of this "mechanic" in future updates, with lots of tutorials obviously.
GG!