Seeking father's sponsorship of a child conceived before marriage

My friend got married to a person whom she met on a matrimonial site and is currently working with Etihad airlines, Abu Dhabi.

She is his second wife now and his first wife and 11-year-old girl are living in Abu Dhabi with him for the last 11 years. Now, her terms with her husband are not good since she got to know of his other hidden affairs too.

She was working in Dubai for the last 2 years when she met him, during which he never told her he is married. She has a 2-month-old boy who was born out of wedlock. She conceived at the end of December 2016 when she was in Dubai, and they got married in India on 7th July 2017.

1. Can the husband sponsor the children of his second wife in the UAE on his family visa?

2. What are the legal charges if the husband decides to confess to the adultery committed by them? Is it possible still from his side to confess and they both are married now, but she conceived the child in the UAE before marriage?

3. Can a legal marriage contract be signed now drafting the terms?