Genesis 2:24-25a: this (one flesh) then that (man and his wife/woman): "Therefore a man shall forsake his father and his mother; he will cling to his wife, and the two of them will be one flesh. Both of them were naked, the human and his wife." [CVOT]here you have not substantiated your claim is the fact that you conflate "one flesh" and "marriage".
And no hurry on your responses. Unless I die in the meantime, in which case my last thought will be about what a loser you were for not exiting your church, convincing your in-laws about poly and giving us your next insufficient argument.