Can a person cite a already married woman as his wife

Three brothers got property under a will of their father. They have partitioned the property into three equal shares.

1. Elder Brother married and begot two sons thereafter he died.
2. 2^nd and 3^rd brothers remained unmarried and living jointly under one roof.
3. The unmarried 2^nd brother had illegal contact with a married woman. During that course and while she was living with her husband, the unmarried 2^nd brother gave a house to that women under a registered settlement deed on 5^th January 2010 wherein he referred her as his wife after that he died of hanging intestate on 30^th January 2010.
4. The aforesaid woman sold that house to some other person on 3^rd March 2010
5. She has taken divorce from her husband on 5^th June 2010.
6. The unmarried 3^rd brother while trying to file a suit against that woman and the person who purchased that house died of hanging intestate on 3^rd September 2010.

1. What is the legal position of the children of the first brother?
2. Can a person cite a woman as his wife while that woman is already married and living with her husband?
3. Is that settlement deed valid?

What are the remidies left to the children of the first brother