When I was growing up, my father was in charge of family discipline. My sisters and I were disciplined by both mom and dad, but according to Dad's rules/leadership. He expected Mom to be a strict disciplinarian when he was not around, but she was required to bring very naughty behaviors to his attention, so he could correct us properly. If our misbehaviors were relatively minor, Mom would put us over her lap (naked, in the master bedroom), and attempt to correct us with the hairbrush or the bathbrush. If our minor misbehaviors continued, or we were guilty of major transgressions, we received Mom's discipline, and were then sent to our bedrooms until Dad got home. When we had an appointment with Dad, he dealt with us in his workshop (still naked, and bent over his sawhorse), where he corrected us with his carpenter's ruler, his leather strap, and/or a stiff-but-flexible “hickory switch”. A bare-bottom paddling/tanning/thrashing from Dad was feared and, as a result, was an effective deterrent against behavior that would earn such punishments. Therefore, workshop appointments with Dad were not a very frequent occurrence. A rebellious attitude was definitely adjusted over Dad's sawhorse!
My sisters and I were also very aware that Dad was in charge of adult discipline. If Mom deserved discpline, she would have a punishment appointment with Dad in his workshop. But, he always said that he refused to make and enforce rules that he was not also expected to follow. If he determined that he was guilty of behavior for which his children or his wife would receive discipline, then he insisted that he receive the same punishments that he would administer. When this happened, he would give Mom the authority to correct him in his workshop.
Was anybody else aware (or strongly suspect) that their parents had an adult Domestic Discipline relationship? If so, were your parents simply open and honest about it, or did you find out in spite of their efforts to keep it a secret?