What are the limits of family intermixing according to the Maliki school of thought, and what should be done when the family insists on it despite the clear harm?

The prevalent mixing between men and women nowadays is forbidden according to the Maliki school and others, whether it is within the same family or not, as long as there are foreign men in the gathering. Ibn Abi Zayd al-Qayrawani al-Maliki explicitly stated the prohibition of this, and Al-Nafrawi explained his saying "and no manifest evil" as being like the mixing of men and women.