Reasobs why Sheila may have been shot in bed:
Everyone else was shot in bed. Except Neville who moved seconds before it was his turn.
Everyone else was shot while they slept. Except Neville who woke seconds before it was his turn.
Sheila would not wake until it was her turn. Thread created yesterday.
A bed shot would certainly immobilise Sheila.
A bed shot would mean Bamber would not have to wake and attempt to persuade, force or coerce Sheila to move.
Bamber would not want to risk Sheila seeing June or the twins.
Bamber resented Sheila's financial support, but had a better relationship with her than Neville and June. He would not want her to wake and suffer more than she needed to prior to death.
A bed shot means Sheila would put no resistance which she may do if woken.
Bamber's aim was to kill Sheila with one shot. This is easier if she is not moving.
A contact head shot while Sheila slept would result in any blood splatter going into the silencer.
There would be a minimal blood leakage as it was a low powered rifle. Nothing would drip onto the bed sheets straight away.
Carrying Sheila the way a groom carries his bride, would not change the direction of any blood flow.
Bamber was strong enough to carry a dead Sheila a few feet.
Shooting Sheila while she slept means he could aim the rifle where he wanted to.
If worried about blood flow onto the sheets, he could put a temporary plaster over the wound.
Bamber's aim was to kill everyone as quickly as possible and then stage the scene. This included killing Neville in bed and then moving him. Taking the bedroom phone off the hook. There is no reason why he wouldn't kill Sheila in bed and then stage the scene.
None of June's blood was on Sheila's hands or feet, so Bamber didn't lead her to his chosen position.
It is doubtful he shot Sheila before the twins, but if he did, he would not want to risk Sheila making a noise after waking her, and the twins waking. Shooting Sheila in bed ensures this happens.
Bamber believed he only needed to fire one bullet into Sheila while she slept. The second bullet was fired in the main bedroom after he realised Sheila was still alive.
Bamber entered WHF totally hyped up. His aim was negate everyone straight away while they slept. Then move Neville a Sheila away from their beds and take the bedroom phone off the hook. He would not be calm enough to attempt to persuade Sheila to get out of bed and walk to his chosen position.
Sheila was shot after Neville and June, and almost certainly after the twins. Bamber had the time to move Sheila directly after shooting her in bed. There was no one to stop him doing this. An instant removal from her bed will mean no blood on the bed sheets.
Bamber could put a tissue of cloth underneath where he was going to shoot Sheila. Any drops of blood would land on this, rather than the bed clothes.
Bamber's first shot did not kill her. However it was an accurrate first shot which did a lot of damage. Suggesting he had time to take aim.