The basis of the 2002 COA refers was, if the DNA evidence did in fact prove that it wasn't Sheila's blood, the conclusion was it was a mixture of June and Nevill's. At the trial and the various appeals, the defence position was that the silencer was used and the blood inside was a mixture of the parents.
Rabbit's blood and other bizarre theories came later on in the 2000s.
Just being June and Nevill's blood would still mean Sheila put the silencer on and then put it away.
She would only put the silencer on if everyone was sleeping in bed & she was attempting a silent massacre.
However both sides agree Nevill would not start phoning Bamber's AM or Chelmsford police after him and June had been shot 9 times.
There is no reason why she would go to the trouble of putting the silencer back in it's box downstairs prior to shooting herself.
It being human blood is very damaging. Sheila's blood confirms guilt.