Dating your brother in law
If one pair of siblings is married to another pair of siblings, the siblings-in-law are thus doubly related, each of the four both through one's spouse and through one's sibling, while the children of the two couples are double cousins.
Please don't interpret anything you read here as medical, legal, or otherwise expert advice. I am 7 months in, and I have visited my bils a number of times, and its very clear to me that they all view me as their sister.
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