Thinking about the kitchen soc from a JB innocent perspective I've always thought the disarray was caused when NB and perp (SC imo) arrived in the kitchen after the shootings upstairs but I guess some of the disarray could have been caused beforehand.
Anyway re NB's found position I don't see anything suspicious in him straddling the back of the chair. He was a tall man 6' 4" with long legs and could easily have fallen on the back of the chair in effect straddling it as found. He obviously could not have remained in an upright position and ended up falling forwards as opposed to backwards?
What I do find a little odd is how NB's head ended up in the coal scuttle without any sort of minor injury/tell tale sign. Although Dr Vanezis didn't make any comment to this effect. Is it possible NB's head was hanging with blood pooling internally and officers, Dr Craig or PC Wright from the coroners office moved NB's head to the coal scuttle for whatever reason(s) thus releasing pooled blood? It seems to me that NB and SC bled out from their gsw's but this doesn't appear to be the case with June based on an albeit poor quality soc image. June sustained a gsw between the eyes but I can't see any blood on the surrounding carpet? Could this be accounted for by the fact June wasn't moved?
The idea JB or SC went about re-positioning NB to burn his back, inflict gsw's on his head, build a blood dam etc is not plausible imo. If JB was responsible he wanted everyone dead and out. If he was concerned about NB living to tell the tale he would be just as concerned about June.