CA Step-Parent Adoption Records

My sister (same mother) was adopted by my father in 1949, after our mother divorced her first husband. I can only assume my sister's father granted consent.

Our parents and my sister's biological father are all deceased. What do we have to do to obtain her original birth certificate, specifically? Do we need a lawyer? She is Native American but cannot prove it without the birth certificate.

Thanks,
Joyce

[CMSC]

I know this post is over a year old but I am not sure if you have gotten an answer.

If all bio parents and adoptive parents are deceased you can go to the county court house that held the adoption and with death certificates of the above parties mentioned and ask that the original birth certificate be released.