I do think that JR had PR write the RN while he attended to other areas of the coverup--some of which he would fail to discuss with PR right away, so they had little crossed signals in the early days when one or the other of them would remember the 'wrong' shirt JBR was wearing, etc.
The reason I think PR went along with things is that I think JR was/is an extremely clever man who committed a crime out of fear of exposure but then had enough time afterward to figure out the best way to get PR's help.
I've always been struck by the 'staging within staging' comments--some from LE, I think? And I think that this crime was staged twice, once shortly after the murder was completed, and then again during the early hours of the morning of Dec. 26.
The first staging was entirely JR's work. He removed JBR's underwear because the staged sexual wound, intended to cover up evidence of molestation, bled more than he'd anticipated. If the blood soaked through the white long johns PR could hardly overlook it. So, he wiped JBR down, remembered that PR had mentioned a gift of undewear for JBR's cousin, opened up a few gifts until he found it, and replaced the pair he took off of JBR with one that was just like it--only far too big. He's counting on PR not noticing the size difference when she first encounters her daughter's body, and by the time LE brings it up he will have told her 'the awful truth' he 'discovered' later, pretending that he replaced the underwear during the second staging, the one PR knows about.
Once JR has cleaned JBR up, he leaves the rope he has used to strangle her around her neck (just rope at this point; not artistically constructed garottes or anything). There is no rope on her wrists, and her body may or may not be lying face up--she may be lying face down, or even sideways at this point. JR then places two more objects near JBR's body before going to get PR. Awakening her, he tells her, brokenly, that something terrible has happened
The two objects beside JBR's body are BR's pocketknife and a single golf club. The inference would be obvious even without JR's story: BR has done this.
JR stresses that it must have been an 'accident,' creating PR's dislike of the word and her reaction to it in the interviews. He probably tells her that BR was half-asleep or sleepwalking; later he may suggest that the trauma of the experience has caused BR to forget the whole thing. Once PR's shock has begun to subside, JR is able to convince her that their best course lies in 'protecting' their son.
Even if PR is aware that BR can't be charged with the crime, what JR is saying makes sense. BR will be taken from them, sent away for rehabilitation, perhaps. He may be kept from them for a long time, sent into foster care, even. Courts may decide that the R's are unfit parents since they 'let' this happen, ignoring such warning signs as BR's first violent attack on his sister with the golf club some years before. If PR is in any way hesitant, JR can play his trump card: PR's cancer may return at any time; she could die without ever getting her son back.
Whatever the case may be, somthing works, and PR leaves the basement and JR. He has suggested the ransom note; I think at that point he may still think he can get JBR's body out of the house. He does realize later that this won't be possible, and despite the change in plans leaves the ransom note--it gives them a reason to call 911, to cancel their flight, and to get friends and neighbors over, which can only help to confuse things.
At some point he has to tell PR about the underwear, and when he does, he suggests that BR has been abusing JBR! This would explain PR's startled "How did you know?" response to the information LE has about the abuse.
Some of the second staging ends up being confused and misleading because there are now two people involved, with two different objectives. JR, for instance, knows that BR hasn't been involved, and so casually leaves the pocket knife in the basement, not far from the crime scene--but he is overheard inquiring about the golf clubs; possibly he is afraid that something will connect the 'staged' club with the crime scene, some minute bit of fiber evidence or something. (Or perhaps he wiped it completely clean, like the flashlight and batteries!) But PR, thinking of a staged abduction scene, suggest re-dressing JBR in the Barbie gown, something JR doesn't want to do--the size 12 underwear are ridiculous enough under a pair of pants, but under a gown they will be a glaring inconsistency.
Sorry this is so long. But one of the reasons I can see JR committing this crime and then manipulating PR into helping with the cover up is that I can see him playing on PR's fears in re: BR throughout the ordeal, and I really can't think of any reason JR would be willing to go along with PR in covering up a crime he'd possibly believe she committed.
