Maggie I cannot answer your questions sorry. It is so difficult to piece together why was the covers not pulled back on Ralphs bed if Sheila did sleep with June and Jeremy could have placed the teddy bear on the bed after the murders does Cal mention this in her book (not read it yet) maybe the boys gave the teddy to Mummy to help her sleep I have not got a clue and get more confused daily.
Someone did suggest that the covers on the far bed in Sheila's room may have been pulled up by Jeremy after the shootings which would imply that Sheila had not gone to bed that night but had been wandering about in a murderous mood?
As for the teddy, I believe JB was telling the truth and it was Nevill's teddy bear. He would probably not have had a teddy when he was young because they weren't really around when he was young, they were called teddy after Theodore Roosevelt so he may have had that one as a present for a joke at some time

however, don't believe he slept with it.