A. You're asking for a lot. An informal poll of my mom friends indicates that you can't realistically expect to be left alone in the bathroom until your youngest is on the other side of 7. My 8-year-old can manage this level of respect and self-control about 50 percent of the time. So, either I lock the door and do my best to ignore her shouts or, if I've forgotten to lock up, I ask her in a firm voice to leave, reminding her of how she feels when she's on the toilet and wants to be alone. She's making progress, but really that's only because she's just old enough to value a little privacy for herself.
This is the developmental key -- your kids can't give you something until they see the value in it for themselves. Preschoolers and toddlers seldom want to be alone, and they think of the bathroom as a good place for a small party, sitting on the toilet while chatting and singing and looking through books together.
Until your children reach the age of reason, you'll have to bear the indignity of a bathroom audience, whichever side of the door they're on, no matter what you're doing in there.
I also used to take advantage of family dinners out in restaurants, leaving the girls with my husband and visiting the ladies room alone a couple of times in an evening, just for the relaxing respite of it. Of course, Madeline and Eleanor always had to tag along for at least one excursion to a restaurant bathroom -- if Mommy liked it, it was worth checking out.