Skimming through your posts, I cannot see any documented evidence attached to them. They consist mostly of wild speculation and conjecture.
Do you believe the police got hold of the rifle found on Sheila, fired several bullets into Junes pillow before pouring her blood over her side of the bed? Because that is essentially what had to have taken place for your argument to be the factual one.
Do not skim read you will miss the point. I am sorry to say that you are beginning to behave like Adam. Creating argument for arguments sake.
My hypothesis is that the police shot June by accident. In desperation they staged much of the crime scene we see still hoping to blame it all on Sheila. Unfortunately they reckoned without the Boutflour Family. As a result of amongst other things police misinformation and their own investigations they 'twigged' what had gone wrong. The blood on the stairs is but one example. As a result of this they were able to manipulate and or work with some police officers.
If this happened they had lied to the inquest covering up their mistake and the whole EP force would be in deep trouble. The families silence and cooperation ensured JB was framed and the family gained the Bamber estate. The police had removed the threat of exposure since it was a Faustian pact. Both sides win or both sides loose.
You may disagree but given the history of this case down the years and the way it has been handled by the Justice System such an hypothesis is not beyond the realms of possibility.