So who is the father?

The guy who was shown bloody and beaten up is the father of both children, she was already pregnant when she met Sovieshit, that's why everyone assumed she gave birth prematurely but nah it was a normal pregnancy, just no one knew

Ohh that explains it! Thank you!

But before Ergy departure, he told Sovieshu that Glorym is his daughter. Meaning Popes lied or something. And with Trashta already dead, there's no way to know the truth. Author didn't tell us clearly whether Glorym genuinely his daughter or not.
It's just after that Sovieshu felt sorry and regret for neglecting his own daugter (from Sovieshu's POV)

He meant it in the way that if he really likes Glorym he can still consider himself as her father.
Also could you not spoil people about future events they did not ask about please ?

I didn't mean to spoil the story here. Just wanted to share my opinion after I've read the novel which author didn't give us a clear answer for this one. It could be Ergy wanted to play mind games with Sovieshu or it could be he told the truth which bring us to Trashta already gone and with that, we don't know how to get the answer unless there will be another methods in the future that doesn't require blood testing.