Is it permissible to benefit from materials provided by a brother who works for a company that sells pork, given that his sister has decided to appraise these materials and donate their value to charity?

Earning money from selling pork is forbidden. If the seller has other lawful earnings besides selling pork, and their money is mixed, then dealing with them and accepting their gift is not forbidden, but it is disliked. However, if all their earnings are from selling pork, then their money is forbidden, and it is not permissible to accept their gift or eat from it, unless there is a benefit in accepting it, such as avoiding the severing of family ties, in which case it should be accepted with the intention of giving it as charity.

Regarding a house built by this person entirely with unlawful money, it is not permissible to benefit from it by living in it or otherwise, except out of necessity. Some scholars are of the opinion that unlawful money, due to the way it was earned and not because of its intrinsic nature, is forbidden only to the one who earned it. As for someone who acquired it from them through a permissible transaction, it is not forbidden for them.