It might have been explained in the ABO Guide that wasn't translated at the start of the story. Some authors do alpha X alpha and their bodies change for an alpha pregnancy and then back, like they grow a womb just for heat/rut/knotting time but I agree, it would have been nice to know how the author's world of alpha x alpha and an heir would have been produced. Each omegaverse author has their own darn ABO universe rules lol

1) If producing an heir is so important in this alpha-only family, how would two alpha males being together work? Wish they would explain that, seems like a pretty significant detail to brush over! Guess they’d have to use special medicine for one to get pregnant or something?
2) both these brothers feel like bad news imo maybe a third option would have been better?? (╯°Д °)╯ one is indecisive and the blonde kinda creeps me out! Poor baby didn’t get much choice I think