i am sure it was illegal until 1907
the dead wifes sisters act was passed in 1907 this meant that you could marry your dead wifes sister ,legally, but the dead husbands brother act wasnt passed until 1921
not sure if half siblings would make a difference as once you got married you were then deemed to be related to that family. their sister in law
i think it was the female was then deemed to belong to the males family, i am not entirely sure if it worked both ways as we know males were seemed to be special
like the married womans property act which was passed in 1882 :~
the 1882 Married Women's Property Act. Under the terms of the act married women had the same rights over their property as unmarried women. This act therefore allowed a married woman to retain ownership of property which she might have received as a gift from a parent.
Before the 1882 Married Women's Property Act was passed this property would have automatically have become the property of the husband. The passing of the 1893 Married Women's Property Act completed this process. Married women now had full legal control of all the property of every kind which they owned at marriage or which they acquired after marriage either by inheritance or by their own earnings