Digging out my 1983 WoG box, I find that Zilchus is the only mentioned LN Oeridian Greater God, thus a likely father. Mothers -maybe Atroa (Spring, East Wind, NG) and Wenta (Autumn, West Wind, CG)? 
The discussion is pretty academic I have to say, but a single LN mother and good & evil fathers would seem like a reasonable explanation - Pholtus is Oerid so he could've been Heironeius' dad, Hextor is the only LE Oerid god mentioned, his dad could've been an arch-devil, or could've been Zilchus ("the love of money is the root of all evil"), perhaps a more interesting approach.

The discussion is pretty academic I have to say, but a single LN mother and good & evil fathers would seem like a reasonable explanation - Pholtus is Oerid so he could've been Heironeius' dad, Hextor is the only LE Oerid god mentioned, his dad could've been an arch-devil, or could've been Zilchus ("the love of money is the root of all evil"), perhaps a more interesting approach.