I did get into the mother's room. I probably missed something there (you mention number 3, I didn't find that). I'll go back and have a look. I'll also check the book by the family portrait, I didn't notice it at all.
I'm very bad at rubik's cube type puzzles, so I just moved it mindlessly and it was funny that I broke it, that is indeed clever. Just to check, I could only move some of the layers of the cube, is that by choice, or did I just miss places where I could click and move others/rotate the cube?