The Unrequested Assist

Anyone who has a child knows how difficult it can be to get them to do the right thing. When you add another kid into the equation, it only serves to complicate things. I love my kids. They're the best and i wouldn't trade them for the world. However, it becomes exceedingly difficult to reprimand or discipline one without the other getting involved.
If Beckett is doing something wrong and we say "Beck, stop doing that", his sister will undoubtedly repeat what we say. So, when we say "Beck, Stop!", she yells "Beck, Stop!!" as well. When Brynn goes into the bathroom, demanding we accompany her, and we say "Brynn, you're a big girl and you can do it alone", her brother gives her the old  "Brynn, you're not a baby! You can wipe yourself." It's frustrating enough to have to deal with one child's undesirable behavior without it causing another undesirable behavior in the other! I supposed it's totally natural and nothing to worry about. That knowledge, however, doesn't make the behavior any more appealing.