NYC Birth and Adoption Records

Hello -- first time poster.

I am researching a branch of my maternal grandmother's family. Her father [Markus] had three brothers and one sister [Gela]. All were born in Krakow in 1890s and emigrated to the U.S. in the early 1900s as young children. In 1911, when Gela was 16, she had a baby and placed him in Catholic adoption. I believe this was so that the baby could not be traced to her (Jewish). She married a few years later and had a daughter.

I met her son in the early 1990s at a family reunion. By then, he had figured out who his birth mother was and was invited to a 100th birthday party for another relative. I regret not asking him more questions and he has since died. I don't know if he had a family -- not even sure of his last name. I'm guessing it might be difficult to get hold of his birth records? If I knew his last name, I could look for cousins.

The other mystery is Gela's daughter, who was born in 1918. Marion's first marriage was in 1938. I've found this husband on other Ancestry family trees -- he is listed as the father of a daughter born in 1938, though Marion is not listed as the mother. It looks like Marion had five marriages in total. She died in 1981. Her daughter (name unknown) had multiple kids with different fathers. Three of these kids are a DNA match to me. Two of them have a name for their birth mother, whom I assume is Marion's daughter, but I can't find any record of her.

Realize this is a long shot, but are there avenues open to explore?

Thank you.