You then have to believe Sheila was acting rationally and therefore not in the grip of a schizophrenic episode, when the "all people are bad and should be killed " remark of several weeks previously re-entered her head.
In my opinion it was Jeremy who crept into the twins' room first to test the gun, disabling the twins with one shot to the head each, then dispatching his parents in the master bedroom with what he thought would be enough with the remainder of the load, returning to the twins' room subsequently to secure in an arc pattern their demise.
None of this typical of Sheila with her lack of synchronization between head and hands, unable to place the final shot to June right between the eyes, nor would she have lain down on the bed with her mother, who in your scenario was the most hated individual in that household. Her whole serene demeanour and blood spatter on the nightie suggests her death was quick, occurring from the sitting position, Jeremy pulling her legs following the second shot to convince himself that she was finally dead.
Well, considering that Ann Eaton was told by Jones and Clark when she first arrived at Jeremy's cottage on the first morning of the shootings, that the bodies of June had Sheila were in fact and had been when they had viewed them there less than an hour previously, laid on top of the bed side by side, with the rifle on the bed in-between both bodies, and that Sheila had a bible on her chest, and that although Ann Eaton remembers being told this because she confirms she was told this as such in her COLP witness statement, but she conveniently forgets the identity of the police officers that told her this that, it can hardly be my scenario that June and Sheila's bodies had been there on the bed now can it? Or am I missing something out which I am not capable of understanding?
Either, the bodies of June Bamber, and Sheila Caffell, were laid on top of the bed when DS 'Stan' Jones, and DC 'Mick' Clark visited the main bedroom carnage, or they weren't. If they hadn't been, why would Jones and Clark tell her that they were, and had been? In the same breath, they told Ann Eaton and the other relatives that Neville Bambers body had been found downstairs in the kitchen, and it was! They told Ann Eaton that the twins bodies were found shot in their respective beds in another bedroom, and it was true! So, why would these two cops tell Ann Eaton and the other relatives within an hour of leaving the main bedoom at the farmhouse, that the bodies of june and Sheila were laid on top of the bed, side by side, with a rifle on the bed in-between both bodies, and a bible on Sheila's chest, if the bodies had not been there, but had been elsewhere on the same bedroom floor either side of the bed? June by the door, and Sheila on the opposite side of the bed in possession of the rifle, and the bible no longer on her chest, but nestled next to the upper right part of her arm, if it had been this way when they visited the main bedroom?
So, please try to refrain from saying that this is something that I might have made up, or even that it's my scenario because I wasn't there in the main bedroom when Jones and Clark were there, I didn't see what they saw, and I had no involvement in what they told Ann Eaton and the others regarding where the bodies of the five victims had been found! Don't shoot me, I am only the messenger!
There is clearly been something very sinister going on regarding the displacement of the two female bodies in this case! It's not me deciding to say off the top of my head that Sheila's body was originally found in the kitchen downstairs, that her body was subsequently found upstairs laid on the bed, and that someone moved her body onto the bedroom floor, or that June's body was laid on top of the bed next to Sheila with the gun resting on the bed in-between both of them, before someone moved her body so that it ended up on the bedroom floor near the doorway - it's evidence readily available to anyone seeking the truth contained in the police files, which I had no control over that which the police themselves were responsible for recording!
These conflicts of evidence cannot be explained away as errors, or mistakes, or typing errors, nobody can make the mistake of seeing a couple of bodies, here, there, and everywhere, and expect anyone to dismiss the devil in the details!