6/1950 Need help w/ St Vincent's Home for Unwed Mothers in PA

I am searching for niece born at st.vincent's april or may 1950.When my mother went to bring my sister and baby home nuns told her it's too late my sister turned 21 May 19 and they had her sign papers and took baby away.No one ever spoke about it but it has always been on my mind.I have had 2 girls contact me but without any info nothing can be certain.So i just pray something may turn up. luck to you