Normally, with adoption, the name of the child changes completely, and so there is no link to the original birth name/certificate.
Your 'relative' married in her birth name, according to you, so must have known more of her background than many who are not even told they have been adopted.
Did she refer to the lady as her adopted mother, and when did she start to regard her as such, presumably there is no Father's name on her marriage certificate? If the adoptive mother married in 1941, did the husband have responsibility for her also?
Yes, if a proper adoption, then he would have been her father at marriage.
I have a relation whose father was born in 1926 in Northern Ireland (before official adoption) but was then officially adopted in 1947.