Why was NB not shot in bed? Why would JB not deal with his greatest obstacle in order of priority? Why would JB shoot/maim June a petite woman of perhaps a slightly anxious disposition before shooting/maiming NB a powerfully built man who was military trained? NB was shot well away from the bed while he was standing. JB was considered a marksman so he would have been more than capable of successful head shots. He could then have fired other random shots to make it appear amateurish/frenzied.
How could he claim Nevill phoned him if both were shot and killed in bed? He needed Nevill out of bed to be able to pretend Nevill made a phone call to him. The phone call was integral to his plan so integral he told Julie in advance about such. The pretend call from Nevill was both his alibi and also a significant part of his effort to frame Sheila.
Saying Nevill called him would not be credible if Nevill had been killed in bed. It still ended up not being credible because he shot Nevill upstairs before he made it downstairs to the kitchen but Jeremy didn't realize they would figure out he was shot upstairs first.
As for what you choose to believe regarding Neivll making the call:
Hearing gunshots would not prompt him to hang the phone up and hang up the phone or just drop the phone and go check it out. He would not take the time to hang the phone up and then take it off the hook so no one can call the house while he goes to check.
In the meantime he would have had no reason to call Jeremy. You ignore that time and again.
1) Why would he leave Sheila alone so she could go threaten June and the boys and why would June stay in bed?
2) If he felt Sheila needed to be disarmed why would he not do it himself? Why would he call Jeremy who would take 15 or more minutes to arrive instead of doing it himself? He was stronger than Jeremy and bigger than Jeremy and of course much stronge rand bigger than Sheila. Why would he want a weaker person who woudl take a while to get there to do it instead of doing it himself? With time of the essence you do it yourself.
3) If he was too scared to disarm her himself without any weapons why wouldn't he grab one of the weapons available in the kitchen to use to confront her with? The kitchen had knives, pokers, guns and other weapons. If extremely worried tyou grab a gun that is the ultimate weapon to use to confront someone with a gun.
4) Jeremy did not get along with Sheila and would have made matters worse not calm her down
5) Jeremy had an answering machine and the phone was on a different floor than his bedroom so Nevill would have gotten an answering machine and had to hope Jeremy would wake up, go to his answering machine, listen to the message and call back.
6) If Jeremy actually received such a call why would he initially do nothing then call Julie? SOmeone actually receiving such a call would phone 999 or rush right over not do nothing and then when finally deciding to do something to call Julie. Worse he lied and insisted he immediately called police though we know for sure he called Julie first. Why did he lie about calling police first? Quite clearly because he knew that gave away the fact he received no such call and Julie's testimony makes that clear.
You also ignore all the evidence that proves Sheial can't have killed anyone and thus there would be no reaosn for Nevill to make a call saying SHeila was running around with a gun.
But as they say ignorance is bliss and since you can make up any nonsense you feel like you don't really care about what the evidence shows...