I honestly think that Sara's daughter is an Icyene that he adopted, and poured his divine energy into, making her a demigod, or something along those lines.
Honestly, this. Everyone seems to assume that Adrasteia isn't godly herself at all. I would even go as far to propose that she might have been part of Saradomin's original family, eventually finding a way to ascend herself when she went offworld. Perhaps to look for a way to get to her obsessively job-minded father, to remind him of his familial duties, or maybe even just to make up for lost time during her childhood. Given that his fanatical striving for order was already present during his mortal life I can't quite imagine him being home a lot to be the father he should have been.
Anyhow, loads of interesting stuff here, definitely keeping track of this thread.