You seriously didn't think I would be coerced that easily, did you?
Ho Ho, the plot thickens. So Sheila was totally moribund, was she? So how would she have been capable of hiding?
But she was still alive when Jeremy was killing his Father. After he killed his mother. So Sheila just sat there and waited for Jeremy to kill her?
At what point did he kill The Twins?
You will have to bear with me on this because I have just picked up on a few things that I see as discrepancies, if I was ever interested in the first place.
But I am ever logical, and there doesn't seem to have been much logic applied to this.
I think she was sufficiently alert to attempt to hide, though obviously not successfully. It seems odd that she was found wedged up tight against her father's side of the bed, whereas if she was totally out of it with medication she might have been killed in her own room.
The whole incident imo happened quickly, within a few minutes at the most. It only takes around 4 to 5 seconds to fire off a 10 round magazine. Sheila might not have realised that it was her brother, but thought it could have been a burglar or someone with a grievance against Nevill. Bamber might have been masked or blacked up to conceal his identity too, so she didn't recognize him. People have different reactions when having a rifle pointed at them, but being dozy and depressed could have made her more compliant than normal.
I believe the twins were last in line. Between them they took eight shots, thought by Vanezis to have been fired successively, which meant the magazine would be almost empty and have needed refilling before he attempted to kill his parents. Hence more time wasted. Shooting the twins first would also make enough noise to waken his parents and put them on their guard, which is why they were first to be killed.