The story has done a great job at keeping the mystery of who the father is in the backround. At this point, in order to keep a element of surprise for us readers, the nature on whom the father is needs to hit hard.
The daughter's ex-boyfriend was introduced randomly and serves no real purpose for the overall narrative unless he is the father and Despite the ex husband lawyer being involved in the story, it would be too obvious for him to be the father and he looks genuinely confused when that notion is brought up.
The mother said that the father of the baby is someone who has high sperm count, which I believe is a young adolescent boy. and based off of this latest chapter, the daughter's ex-boyfriend seems to be very much around and involved. As we saw him with the mom and the lawyer ex husband. You could assume that he's just being there for his ex girlfriends mom because she just had a baby but that reads the little too suspicious. A boyfriend or a ex boyfriend wouldn't be that involved if anything he should be at the shop helping his ex-girlfriend take care of things. But rather, he's with her mom... Something's not adding up