It happens seldom in my family b/c most of time I take my girl to activities . If I am not present, my husband will ask a family friend to take our daughter to the bathroom.
公共游泳池的更衣室不同, 女厕所有单独的隔间, 可是在更衣室, 大家都赤裸的走来走去 It is reasonable to have the opposite-sex children to change somewhere other than the change room, for example, some pools provide a tent, or your own car or under a towel.
the rule of our high school pool is that no kids 4 years and older can enter the other gender's locker room. No exception. In public area, I once saw a 8 or 9 year old boy who covered his entire head with his shirt and stood by the woman's room entrance, facing down, while his mother was inside. I also saw discussion elsewhere that a lot of American people prefer this way for kids 5-9 years of age. Pre-teens are safe to wait outside of the room, I think. For 2 or 3-year-old girl, I don't think it's a big deal for daddy taking her inside, as long as the dad uses a little bit of caution.