@Reademup If you go back to chapter 5, there is a depiction of what all her children may look like on page 34. Not sure if the author plans to stick with that or if they will look different, but the demon woman that is taking enter stage has the same hair color(I think? This is black and white, so...) and her horns seems similar to An's. Given that An was briefly being taught seduction by the succubus attendant(which will likely continue later on) and the skimpy outfit An was presented with before it was rejected by her mother, I wouldn't be surprised if she ended up like that woman in the picture and tries to seduce the hero once she's all grown up. The brother on her left(our right) could be the second child, assuming the second child is not instead the other sibling on her left wearing the hood.
Edit: Looking back, it seems like most(maybe all) male demons have their horns pointing up and female demons pointing down, so saying the woman in the picture has the same horns as An doesn't matter all that much anymore. I can't tell if the sibling furthest to our right with the book is a man or a woman though, but if we assume their horns are any indication then they are likely a man. With that said, it still makes sense that the eldest sibling would be the one taking center stage, so I'm pretty sure that is what An will look like if the author sticks with that depiction.