In Bible Now, HB scholar, Shawna Dolansky writes

In Israel (and among many other peoples) in biblical times, men could have many wives. They could also have other women—concubines—in their homes along with their wives. Men with two wives, or even harems, had opportunities for group sex and for voyeurism of female homosexuality. This is a common male fantasy.
...
It may be hard for us to grasp how very different it was to live in a world of polygamy. Today it is a fantasy for men, which they can view in these venues, but for men in the ancient world it was an option, at least for the men of wealth who could afford it. They could arrange it, see it, even participate along with it on any given night. For those who believe that the biblical law codes were written by men, men were not about to forbid female-to-female contact.
p. 13-14

Do we have any evidence or extant descriptions of group-sex or voyeurism from the Ancient Near East that was contained within the extended household/clan?

I know there's descriptions of orgies, but that doesn't necissarily involve household members.