Her husband had a child from Zina before he married her
10-6-2009 | IslamWeb
Question:
Assalamu alaikum i would be greatful if you could answer my query, about two years ago before me and my husband got married, he committed zina with a women and got her pregnant. Since the child was born my husband has only seen him a few times which caused major problems in our marriage. For this reason i went to a scholar to find out the ruling about this situation. He told us that the child can not be attributed to the father as he is a child of the bed, however some people have advised my husband that the child does have rights over him therefore he must provide for it and bring it up as a muslim. They have also said that, had the child been a female does that mean he would be allowed to marry her as the ruling states that the child belongs to the mother. I would be most greatful if you could further clarify my query to refute what these people are advising my husband Jazakallah.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
This child should not be traced back to your husband, rather, he should be traced back to the husband of the woman if he had committed adultery with her while being a wife of another man, and her husband is obliged to spend on the child and nurture him. If at that time she was not married, then the child should be traced back to his mother and she is the one who is obliged to spend on him and nurture him. This child should not be traced back to the fornicator or adulterer and he is not obliged to spend on him or nurture him.
On the other hand, if this child is a girl, he is not permitted to marry her according to the view of the majority of the scholars 
and this is not for being his daughter but because of the existence of doubt because even though she is not Islamicly traced back to him, she was created from his sperm, and the issue of considering a woman lawful as a wife for a man is something that has to be avoided for any doubt.
For more benefit, please refer to Fataawa 91096 and 85430.
Allaah Knows best.