Although the relationships shown in the table above are prohibited from marrying, a woman may marry her brother-in-law, and a man his sister-in-law.
However, marriage between the people in these examples is possible - if both are widowed and over the age of 21. So a woman could only marry her son-in-law if neither her husband nor her daughter are alive.
If the previous marriage of either or both has been dissolved in divorce and one or both ex-spouses is still alive, or if either of the parties is under 21, then a legal marriage between them is not possible.