Just to ask, Lev 18(KJV) notes, Thou shalt not uncover the nakedness of a woman and her daughter, neither shalt thou take her son's daughter, or her daughter's daughter, to uncover her nakedness; for they are her near kinswomen: it is wickedness.
- I'm a proponent of being sex positive about intimacy between a man's wives, including threesomes, foursomes, etc. However, that isn't a blanket approval, because Leviticus 18 reigns over this subject area, so -- if a man has wives who are blood-related to each other, then those women shouldn't even be in bed with you when you're having sex with their blood relatives, much less having sex with each other, because those individuals are near kin. The euphemistic phrase, 'uncovering the nakedness of," always implies penile/vaginal penetration at the very least but is worthy of caution even in the case of two sisters -- or a mother and a daughter -- watching each other being penetrated.
- Mother and her daughter are prohibited from having sex in front of each other in Leviticus 18:17 because they are near kin. Period. Mother and daughter are not prohibited from marrying the same man. To come to that conclusion requires inference combined with preferential personal interepretation. But if threesomes were absolutely prohibited, the particular example wouldn't even need to be mentioned.
When it mentions that "thou shall not take" referring to her grandchildren, is this reffering to sex or marriage?