Adoption Certificate for an adopted child

Dear Sir/Madam, Accept my deep gratitude. The query is that my aunt adopted a boy child over 14 years ago without adoption formalities done through a doctor as the kids biological parents were no more and so is not the trace of guardians. However, at that time the doctor managed to get birth certificate sorted on my aunty and uncle name as child's parents by skipping all adoption process. Hence they do not posses the child's adoption certificate and also have lost contact with the person/doctor at the hospital who seem to be retired. Now my aunt and uncle wants to go through legal process to get adoption certificate and then a new birth certificate as it has become important for them to have these documents sorted. Please advice what can be done in this situation so that adoption certificate can be obtained plus a birth certificate by ignoring existing birth certificate of the child and my aunty and uncle become the legal guardian of the child as per the law. Location: Karnataka Child's age: 16 years old now Regards, Raf