through breastfeeding, for example, this is a mistaken assumption concerning the marriage contract, because he entered into a contract believing it to be valid, while the other had intercourse believing it to be lawful. Thus, if she bears a child, that child inherits through two ties, and he is given inheritance through both ties because both causes exist. Whenever a cause exists, its legal consequence must be given effect.
It was also said that he inherits through the stronger of the two ties, receiving only one share of inheritance, because two opposing ties cannot coexist in one person. Since this is impossible, the stronger tie is taken, and he inherits through one tie only.
His statement, “There is no inheritance through marriage to a woman who is an unmarriageable blood relative”: an example is a man who marries a woman and then dies, after which it becomes clear that she was his sister through breastfeeding. Does she inherit? The answer is: she does not inherit, because it becomes clear that the marriage was invalid. Therefore, she does not inherit, even if she had remained with him for many years.
His statement, “Nor through a contract that would not be upheld if he embraced Islam,” means that there is no inheritance through a contract that would not be upheld if he embraced Islam. An example is when a Magian marries his sister and then dies while she is still his wife. If he were to embrace Islam, this marriage contract would not be upheld. This differs from a prohibited marriage contract whose cause of prohibition has ceased, in which case the contract is upheld. For example, if he marries his wife’s sister while he remains married to her sister, the marriage is invalid because a man may not be married to two sisters at once. But if, upon embracing Islam, he separates from the first wife, the marriage becomes valid because the impediment has ceased. Likewise, if he marries a woman during her waiting period, the marriage is invalid; but if he embraces Islam after her waiting period has ended, the marriage is upheld.