What are the boundaries of the relationship between a man and his female relatives who are not his mahrams, and is it permissible to eat with them at the same table or to discuss general matters, and what is meant by "as much as needed" in the permissibility of speaking?

A Muslim's treatment of his foreign female relatives is the same as his treatment of other foreign women; it is subject to the controls of Sharia. Thus, it is not permissible to be alone with them (khulwah), nor to shake hands with them, nor to speak with them unless there is a need. A need is that which, if left, would cause a person hardship and difficulty, such as a man speaking with a woman in matters of buying and selling, knowledge, fatwas, and judiciary. A man eating with a foreign woman is permissible with controls.