It has always troubled me that my bio dad’s name has never been on my birth certificate. Actually, it really ticks me off that my adopted dad’s name is on it now. I really wish it had never been changed.
I have no issue with my mom’s husband adopting me, but don’t feel that my birth certificate is the place to have it noted.
As a genealogist who has questions that will never be answered thanks to ancestors who saw nothing wrong in fibbing, fudging, lying, inventing, misremembering and plain ol’ omitting any detail they found slightly inconvenient, I urge your sister to remember that this certificate will go on existing long after everyone involved is dead and buried. Give your descendants the gift of accurate genealogical information instead of taking a cheap shot at an ex.
Don’t forget Social Security. If the father is indeed crazy and becomes disabled it will be easier to get payments for the child through SS if the dad’s name is on the certificate. (Or if he dies)
it’s a huge assumption that it is all the father’s fault too.
When my sons father died this was very important to him getting survivor benefits.