Jan I have thought that Sheila may have been on the double bed with June and Ralph in Sheila's room but what puzzles me the beds in there do not look slept in although AE did say she was surprised the other bed (not Sheila's) was made up ready for sleeping in. As you have quoted none of us know what happened we can only speculate and that includes Adam.
I just say what I think happened.
To be fair my detailed point by point scenario matches the crime scene and bullet allocation. CAL has a slightly different scenario, and so do the police. But at least they have scenarios, unlike supporters.
Or I give my opinion on other peoples views. Jan thought Sheila may have just been waving the gun around. Or that Sheila had forced Neville to call Bamber. Of which I gave my opinions.