A man having intercourse with a non-Muslim woman, having a child, and attributing the child to himself

Q: I heard about a widespread case. Some Muslim expatriates marry Christian women without marriage contracts. They meet such women and agree to live with them then they beget children. These children are given Islamic names and attributed to the men who had sexual relation with the mothers. These Muslims claim that the women with whom they had sexual intercourse want, at their discretion, to sincerely convert to Islam. My question is: What is the solution if such women convert to Islam and these men separate from them, then later marry these women with lawful contracts? What is the status of the illegitimate children?

(Part No. 20; Page No. 391) A: First, the agreement concluded between these persons counts as an agreement on adultery, which is prohibited according to the Qur'an, Sunnah and Ijma` (consensus of scholars). Such Muslim men must perform Tawbah (repentance to Allah). As for the children who were born as a result of such relations, they are illegitimate children who are to be attributed to their mother, not to their father by any means. Second, if the woman converts to Islam and they both perform Tawbah, the man is allowed to marry her with a lawful contract. The children they beget under this new contract are to be attributed to both of them. May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions.