I am not buying that Opal would be so quick as to welcome Rob Gardner into her family. Opal has been a less than forgiving person in her history, that's why she and Erica are such good friends.
In the 1995/96 era when Enid Nelson reappeared on canvas, Opal was quick to shoot her down for all she did to her Jenny.
What Enid did does not even amount to what Ray did: A) Force Opal to leave Adrian behind so as to keep him alive; B) Leave a battered Tad on the side of the street to fend for himself; C) Use physical forced to get Opal to manipulate her relationship with the Martins.
Rob is cut from the same cloth. It does not matter how charming he is, Opal has made it clear in the past that she wants nothing to do with anything Gardner. I think that includes Ray's little brother dearest.