What is the ruling on the salary of the husband of the wife's sister, who works as a confectioner in a hotel that involves some forbidden things in its operations, and is it permissible to eat in his house?

If the confectioner's work involves making sweets forbidden due to containing carrion or impurities like pork and alcohol, then his work and earnings are unlawful, and it is not permissible to deal with him or eat at his establishment unless he has another lawful source of income. However, if his work is generally permissible, but he occasionally makes forbidden sweets, then not all of his earnings are forbidden; rather, a portion of them would be unlawful. In this case, his money is mixed, and it is permissible to deal with him and eat from his food. He should be advised to stop making forbidden sweets.