Is it permissible to sleep in the same room with the husband's younger brother, with the husband also present in the same room, and each of them on a separate bed?

The fundamental principle is that the wife should reside in a dwelling separate from her husband's brothers, due to the Prophet's (peace be upon him) prohibition against entering upon women. He warned against the "hamw" — who is the husband's brother or relative — and described him as "death." However, if extreme necessity or dire need dictates that the husband's brother stay with the couple in the same place, then there is hoped to be no harm in that, provided that he does not seclude himself with her and that she observes hijab in front of him.