Is the mixing of the wife with her husband’s unmarried brothers in one house, and the mixing of male and female relatives and neighbors, with only the face and hands uncovered, considered unlawful mixing?

The dwelling of non-mahram relatives in a single residence with shared facilities is forbidden due to the potential for seclusion (khalwa), mixing, and unlawful gazing, and because the eye cannot be protected when it is let loose. The fundamental principle is that family gatherings should be free from mixing between non-mahram individuals. However, if a gathering occurs that is free from suspicion and in which the legal (Shari'ah) controls are observed, then there is no objection to it.