Kinda don't want Liliana to be with the MC at all, all things considered. I really like her personality and her as a character though (even if I'm not a fan of her body, I can appreciate the diversity of options of bodytypes in the harem).
No, I don't want her in the harem at all because in order for that to even begin being a real possibility, Athagan would need to be dead. I really don't want him to be dead. Maybe if there's a timejump to 15~20 years into the future and he died of old age, then fine (it'd also make Liliana pretty old by then though).
I suspect that if he does die as part of the story, it'll probably be due to demonic machinations...
I appreciate good writing, and good deaths in particular (that serve a good/big purpose narrative wise instead of just shock factor), but if/when Athagan dies, that's gonna hurt. Just let him have the joy of being a grandfather to multiple brats before he goes, and give the opportunity to pamper them rotten before some catastrophe occurs please! Guy deserves it.