A distinguished scholar from an important Torah institution in France told me that he would occasionally come to Israel to visit his father-in-law and mother-in-law. One day, his mother-in-law decided that she also needed to sing zmiros and began to sing with his father-in-law at the Shabbos meals. Since she was doing this even when he was visiting them, he didn't know how to politely tell her about it. He met Rabbeinu [Rav Avraham Genechovski] in the shul near the Chebin Yeshiva and asked the Rav what he should do.
The Rav told him, "I'll give you advice. Approach your mother-in-law and say to her, 'You see, the zmiros at your house are indescribable and beyond compare. The soul simply soars, and the fact that you join in the singing is beyond words, adding so much to the feeling of the song. However, I have a personal problem with this because, since I live in France and only come to Israel occasionally, I am obligated to observe the stringencies observed by the rabbis of France. Since Rav Avigdor the Frenchman and Rav Elchanan the Frenchman, who were Baalei Ha-Tosfos, maintained that a son-in-law is forbidden to hear his mother-in-law's singing [because they follow the gemara:-)], I have a personal problem with this, and I apologize and ask for your consideration.'"
And indeed, he did so and succeeded in politely ending the problem.
