What is the ruling on handing over to the police a son born from an illegitimate relationship, and is it permissible to perform a hymen repair surgery for a sister who gave birth to a child from adultery before her marriage?

The sister must repent to Allah for the sin of adultery. The child is attributed to her, and she is responsible for his care and financial support. It is not permissible to abandon him or cause him to be lost. You (plural) must help her in raising him and treating him with kindness. You must conceal her secret and not tell anyone what happened. It is recommended to marry her off to someone whose religion and character are pleasing. As for hymen repair surgery, it is not permissible.