Two nuns were walking along a street, when they met a man, one of the nuns went up to the man and kissed him. The second nun reported this to the Mother Superior, and the first nun was called in to explain herself. When asked who she had kissed, she replied. "That man's mother is my mother's mother-in-law". Who was he?
I don't understand that one weecalf.
I have been a mother for nearly 40 years, but I was not a mother in law until my son got married. So I can't see the reasoning.
If you had said it the other way round it would have made sense to me.
Still, Schutzengel seems to understand it.
The reasoning why, not being overly serious was that in law every mother is legally the mother of her children .So why is the parents of the wife /husband referred to as Mother /Father in law .I dont know .
Weecalf.
The mother of the husband has the courtesy title of mother-in-law to the wife. And likewise the mother of the wife has the courtesy title of mother-in law to the husband.