Children's Home Society Adoptions

Hi......my grandaughter was born in Buffalo, NY sometime between 1973/74. Her mother, (my daughter) is deceased and I am trying to find this grandchild. My daughter had severe mental disabilities and when the baby was 3/6 months old my daughter left the child alone. I don't know who reported the incident but the child was taken away by some organization. I was living 3000 miles away at that time and never knew any of this till three years ago. I have posted messages on many sites and even paid an investigative agency of good reputation. So far all is in vain. I now have paid an intermediary to petition the court due medical purposes. I have advanced cancer along with other deseases that can affect other biological members of the family. Do you think this will be successful? I vowed to find this child as she has 3 half sisters who are desperate to meet and know her.......Sincerely........Antoinette