Once you slog through those early threads, look up the interviews with the SIL and FIL. The one with Ronnie (FIL) in the interrogation just after the murders, then 1 with MIL and FIL with Colorado media, and the long one with MIL/Colorado media. This is how they treated SW, even after CW had plead guilty via the plea bargain to murdering the whole family. Just before the sentencing.
Then, look up on YT the book of Cindy's (five chapters) that was leaked about a year ago (?), and was nearly completely roasting Shan'ann. The whole thing was released and discussed word for word by many sites.
Just for a quick understanding of how they treated her, look up the short video SW posted of the day that MIL/FIL arrived in Denver and how they treated SW on a simple stroll through downtown with SW, with CW and the girls. Cindy couldn't have portrayed hate any more clearly.
I couldn't say that he was more likely to murder because they hated SW, but they created him, and ultimately made her life like hell for 8 years trying to insert a wedge between the couple. I just can't imagine marrying with the groom's family refusing to come to the wedding. IIRC the grandma and an uncle came.
While back east, SW texted that Cindy was trying to influence Bella, telling Bella not to tell her own mother certain things. Trying, IMO, to break the trust between Bella and her mother. I haven't seen absolute proof yet that MIL/FIL knew about CW's affair with NK yet, but there are accounts that they, or at least one family member knew from the beginning. And, NK told LE that she heard about "nutgate" from a third party, ie not CW. IMO it was clearly a family effort to create problems between the couple.