My long shot is that the Dark Urge Character is actual one of the children of the now deceased Bhaalspawn. Maybe Abdel's, Maybe Imoen's, Maybe Sarevok's, etc. I mean Sarevok was married. That would also make ANY race/gender combo cannon as any of the Bhaalspawn could have sired progeny. Bhaal blood is potent and these would be grand children of a god. IIRC Bane only had one demon child and he resurrected through him alone.

Basic Tav is also possibly cannon, simply because the number of victims abducted. Each and every one of them could be Tav. What I am saying is that the both DU and Tav and all of the origin charecter's are cannon if the story is written correctly.