Just to be clear, we are talking about his biological twin sister here, not his adoptive sister. Apparently his adoptive sister was one of the few family members that Russhole actually had a good relationship with up until she got engaged. Then he got all pissy and jealous because she was getting all the attention instead of him. When the engagement/wedding announcement went up on Facebook, Russ was just as petty and childish as you'd expect, leaving a passive-aggressive "angry" reaction on the announcement and leaving salty posts about how he wasn't informed. He wouldn't have been able to go to the ceremony/sealing in the LDS Temple since he left the Church and was no longer a Temple worthy member in good standing, but he still could have gone to the reception. Still, he initially stated he wasn't going to go. His father drove down from Evanston to take him to IHOP and try to talk to him, either trying to calm him down and convince him to go, or warning him that if he does attend that he would be forbidden to talk about Taylor Swift, frivolous lawsuits, or prostitutes and brothels. On the day of the wedding, like an hour or two before it was to begin, he started trying to convince people to come to Salt Lake to pick him up so he could go...about three hours round trip with good traffic. No one did.
I believe he's been invited to Greer family reunions and gatherings, but always with the warning that he needs to keep his selfish interests and bullshit to himself.