Hello, I'm new

been lurking for a while but finally joined after reading this as - so far - I have not seen anyone else post my theory..... I have always been on the RDI side, but didn't put too much thought into who exactly
So, I agree so far that JBR was put to bed already asleep, woke up, went looking for BR (or even just for something to eat) and ate the pineapple with him. Then, I think they were playing in the train room. BR put the cord around her neck as part of a game. He has whittled the paintbrush into a handle for her "leash". Now, I think BR has at this point been abused by someone (highly suspicious of older bro...) who is either also abusing JBR, or BR is just passing on his problem. This time, while they are playing a game involving her being tried at the neck, he jabs at her with his finger, leaving woodfibres from the paintbrush that were on his hands. She yelps, and in his panic from the noise, he hits her on the head. She falls to the floor and he runs from the room. JBR begins to fit from her head injury, however now the cord is tightening around her neck due to the movement. Over time, her movement tightens to cord enough that she is strangled by it, causing her death. PR is still packing and happens upon JBRs empty room, this is potentially (if it happened) where the "where's my baby" comes from. She finds BR who is shaken, and then she finds JBR and screams. This wakes JR, then he does the cleaning up/redressing while she writes the note.