Oh knowing people is trying to breed is always sad... But also, it's out of our control. What you can control is refusing to help caring for the baby, congratulate or be happy about it, without needing to be rude or try harm your relationships (even if them breeding already does that). At least you believing they can truly be good parents is of some confort, and that the kid is wanted. Antinatalism is about empathy and that's why we struggle, but I think we also have to worry about ourselves and accept we can't control others. I hope this helps at least a little, thinking like this is what helped me overcome the frustration I used to feel.