You make some very interesting points about this and it's something I never considered before. The more I ponder this, I think it is entirely possible.
JW and his family were determined enough to get custody of SW that they committed mass murder and this is what is so perplexing. Why murder HR's family members? If JW was SW's biological father, the only person who stood in his way of getting custody of SW was HR, JMO.
I've assumed the statutory rape charge was tied into SW, but it's also possible that during the investigation, LE came across something like old emails that showed JW had sex with HR when she was underage.
What I struggle with is why would HR allow JW to have visitation with SW if he wasn't SW's biological father? He would have been nothing more than an old boyfriend who was harassing HR and he would have had no rights to SW whatsoever.
Also, I'm not sure it's ever been confirmed that the reason CR Sr. bought the new home was to negate JW's attempts to get custody, but the timing of everything seems suspicious this may have been the case. If JW wasn't SW's biological father, wouldn't they have just told him to go pound sand? It seems to me the R's were concerned about the possibility he might win custody.
I'm totally open on theories. Dewine seemed to almost promise us that we will be blown away when the details come out in court.