Didn't we see from the wolf's PoV that last Ay being rescued? I think it was a vision Baaljagg gave Toc. I'm certain the figure who saved Baaljagg was female.
Edit: nope, my mistake.
The scene:
Quote
Then, standing before her, a figure. Cowled, swathed in roughly woven black wool, a hand - wrapped in leather straps, down to the very fingers - reaching out. [...] The touch, Toc realised, of an Elder God. And a voice:You are the last, now. The very last, and there will be need for you. In time...
No sign of gender. The straps are probably a clue. Anyone remember any other God being referred to as wrapped in leather straps?
Another point: Elder God. Envy and Spite are Draconean Ascendants, not Elder Gods. Nor was Sheltata Lore an Elder God.
Trying to get a timescale, this God started searching for a soul for Baaljagg not that much time after the Tellan Ritual, and found the soul of Fanderay after the Fall. Sheltatha Lore had her kids with Draconus and was imprisoned long before that, but when she was imprisoned Sukhul Ankhadu and Menandore spoke only of Envy and Spite as her children, so I think we can be sure Envy has no brother by her. As hs been said, might just be a figure of speech, referring to Elder Gods as her 'siblings', or it could be a child of Draconus, perhaps by Tiam, since that seems quite popular in the extended family.