I suspect it would make IDI happy, as RDI would be forced to pick a horse and then explain the rationale.
I'll go first. I suspect JR and PR. I see no evidence of BR being involved. One can speculate, but there is nothing beyond speculation.
With PR we have the RN and the practice note, both (IMO) in PR's handwriting. We have fiber evidence on both of them. IMO the DNA doesn't clear anyone, it just suggests possibilities; touch-transfer from a male child at the Christmas party. An intruder killer. An intruder guest. We don't know who's DNA it is, or how it got there.
I suspect for most juries the existence of the unknown DNA would serve as reasonable doubt. No chance of ever getting an RDI indictment in this case, much less a conviction.
Aside from the DNA little to nothing about IDI theory is convincing, to me.
By process of elimination, the probability is, IMO, PR/JR. Intruder is possible but much less probable. BR involvement is possible but strictly speculative.
Of course, at trial, the standard would be "Beyond a reasonable doubt". Not Preponderance of the evidence.