You discover your wonderful one year old child is, because of a mixup at the hospital, is not yours. Would you want to exchange the child to try and correct the mistake?
So, my initial thought is that because I spent one year with the child I thought was mine, I already invested in so much love and care into their well being, I don’t want to give the child up. It would be devastating for the child even at a young age to be suddenly switched to essentially strangers and be messed up for the rest of his/her life.
I would, obviously be upset by the mixup (which parent wouldn’t) and I’d probably want to talk to the other parents and be involved with my biological child’s life if they want me to and vice verse. I think there should be some kind of agreement to stay in each other’s lives and then when the children are old enough, tell them what happened.
Of course, there’s all the legal entailment of the mixup so if both parents can agree to my above mentioned thoughts, then I would try and make it legally right. Because in the end, it’s about the child’s mental and physical well being and if they’re already attached to you and yo already loved them, then why not keep them where they are?