Not sure if we are in the right spot

I am a family member of an adoptee.. My mother in law was adopted.. She was born in Sept 1958 in Missouri .We are looking for her birth mom, all she knows is her birth last name is follmer. It was an illegal adoption done by a Jesuit Priest that at the time that knew of a couple that was interested in obtaining a baby... basically, she was taken from her biological mother, and given to this couple by this priest. No papers were ever signed, but her birth certificate that she can see just states her name and date of birth.. She was older than a newborn when this went on, so we know her moms name is on the original certificate. So why would her records be sealed ? Is there away to get the information on them ? Any help on where to start would be so appreciated Thank you