Breed my Cousin

My cousin is 5 years older than me and confined to a wheelchair. We've always got on very well, and when her mother died, I moved in with her. We're both financially well off, and my cousin started getting depressed because she would never be a mother. After attending a family Christening, she became more depressed than usual. I offered to get her pregnant, expecting her to refuse. She accepted instead, so we started sleeping together, and after a few tries, she finally got pregnant. As far as the family knows, she had IVF, and the father's name is a secret. But it wasn't the end of the matter; our mutual grandmother said we had to have a father's name on the birth certificate or people would think bad things about the child and mother. At first we tried to ignore it, but she persisted. As we have the same surname, my mother and her father are siblings, and it would quieten our grandmother; my name is now to be on the birth certificate. The reason I got my cousin pregnant is that it is very hard to get IVF if you are single in our state. But the family doesn't know that.