Can Daedra have children? I know the Princes can, but about a Dremora? And if it's with a mortal, is the child mortal or daedric? From what I've gathered, they can, and the child will be mortal. But what about DaedraxDaedra. Since they're immortal and just reform eventually, having children would be, overpowered.

No daedra can have children. They can not create anything. They can only change. They have always been and always will be. That's the conundrum between the aedra and daedra. Daedra don't have the imagination to create something new, they can only change and twist and manipulate things that already exist, though they can do this in strange and beautiful ways. The aedra on the other hand can create, but their creations are mundane and orderly and follow a sense of logic and pattern.

Any daedric "children" would not be literal children. They'd be proteges or beloved / favored minions or a cherished apprentice.

Now, there is Umaril who is supposedly the child of an ayleid and a god. If true, this was likely not a literal union but a daedra manipulated / mutating a child in his image, or an aedra creating a life and letting a woman give birth to it (I cant remember if the god was daedric or aedric)

Really? Damn. Thanks for telling me then. So whenever anything states Daedra have children or six, it doesn't mean they literally did it. Like Lamae Bal and Molag Bal? Molag Bal just, defiled her soul? He didn't literally [censored] her?

Oh no, he actually did go all the way. Daedra do not produce any children in the act, but it most likely twists the mortal in the process. Lamae was killed and subsequently turned in to a vampire through the act, but given Dawnguard makes it rather explicit that the acts is very unpleasant. In this case, the victims are effectively the children of said Prince, in this case, even going far enough to call them daughters.

Lesser Daedra are a different case, but given the fact that several Dremora flat out state what they'll do to your corpse...yeah, it probably happens.

Can you, if you remember, tell me where it tells of all this in game? I've never found anything, or maybe sadly overlooked, that tells about this.

http://www.uesp.net/wiki/Morrowind:Anhaedra flatly states it in Morrowind, but I guess I misremebered it being generic Dremora dialogue. Still, I highly doubt there's no precedent for such a thing. As for when the topic comes up in Skyrim, its when Serana and the PC are discussing the origins of Vampires and Daughters of Cold Harbor in general. It doesn't flat out use the word [censored], but the implications are very obvious.