What is the ruling on marrying another woman with the intention of taking an ovum from her and implanting it in the current wife's womb to bear a child attributed to the couple? And what is the ruling on marrying another woman with the intention of natural procreation, and then attributing the child to the current couple after the biological mother's consent?

It is not permissible to implant a woman's ovum into another woman's womb, even if she is a second wife to the same husband. The Islamic Fiqh Academy has stipulated this. A child may only be attributed to their biological parents, as Allah Almighty says: (Call them by [the names of] their fathers; it is more just in the sight of Allah). Adoption is forbidden due to the corruptions it entails, such as inheritance without right and the mixing of maharim (unmarriageable kin). The aforementioned method of insemination is not permissible, nor is attributing the child of the second wife to the first wife. The solution is for the husband to marry a second woman, and the first wife can raise some of the children of the second wife to console her. If marriage to a second woman is not possible, it is advisable to care for an orphan without attributing them to you or your wife.