Disposing of hair, nails, placenta, etc. after childbirth

I have been blessed with a bay boy in January 2024, Alhumdulillah! I have with me the belly button which fell from the baby's umbilical cord after a few days when the baby was born. I also have with me his hair which I had got shaved on the 7th day. So my question is:

1. I would like to bury this belly button so called (umbilical cord) and the hair of the baby in the graveyard as I think it would remain safe in the corner of the graveyard in the mud or can I bury it in the grave of my late father? Is is permissible to do this or not? As nowadays there are flats systems so one finds it difficult to get mud everywhere.

2. My family members are saying to drown it in the river as it will be safer there and not in the graveyard. They are saying that if there is a masjid and it has a ground or yard one can get it buried there.

What is the proper way to dispose these body parts like hair, nails, placenta etc. in your opinion?