Sometimes two characters can have a plural amount of (generally familial) relationships with each other. The relationships involved are often contradictory if not mutually exclusive. Such as cousins also being adoptive siblings, or siblings also being in-laws, or adoptive siblings who later married. This is a minor detail but it's already causing tagging issues, and since there is no guideline it's difficult to garden them.
In these cases, should the characters be tagged as both, one of the two, or none? For example I've seen Maomao and Lahan being tagged as adoptive siblings and cousins, Kuchiki Rukia and Kuchiki Byakuya being tagged as brother and sister and brother-in-law and sister-in-law, etc.