We aren’t privy to all of the backstory. My Dad cheated he could have gotten someone pregnant in a midlife crisis and it was a horrible divorce. You might not have met her or the baby. Frankly, as an OB nurse unless you are or have been through something like that there is no way you could understand. I honestly lost all my parents, on my children’s birthday’s. For some it doesn’t compare to a the loss of a baby but the death of my Mama left me in a deep depression. I couldn’t move some days or leave me bed. My therapist took me out 12 weeks. It was unimaginable pain. She was my rock, my friend and confidant. She loved my sister and myself so much. Watching that was the hardest thing I have ever done. I also have a child with an inoperable tumor that surrounds her trachea we had to debulk it because her airway was almost cut off. We were warned she could end up with a trach. She staying in PICU intubated for 3 days to decrease the chance of swelling. It came out fine and we are stable but it does have an increased chance of becoming cancerous. It runs along a nerve pathway and is inoperable. I also had issues getting pregnant and had a miscarriage and almost lost one of my other babies. Honestly they need to have a therapist dealing in newborn and perinatal losses and discussed this issue with them and found a compromise. Now they need to discuss this with a therapist or the Dad does to see how to mend this with his daughter. Even if she is 25 yo you are the parent and as a parent you need to reach out to them.