Tere @Ines, since your mother no longer posts perhaps you can answer.
As a married woman there are, of course, times when she would be completely out of her belt when she is with your father. However, excepting those times, does she sleep in her thigh bands like you do? Unlike you, she is "supervised" when sharing a bed with your father and would arguably not need the extra "security" they provide. However I know your family is very into "fairness", with equal rules when possible for all of the women in your household.
