Uninvited doesn't deter

So, I'm trying my best to get a couple of CME hours doing an online course. I'm sitting on my rocker in the playroom so I can supervise the children while I work. Amy WAS happily playing by herself until I showed up. Then, she immediately wanted me to play with her. When that was denied she proceeded to try and climb up on the chair so she could "sit by me." I very calmly told her that she "wasn't invited" to sit next to me and could find another place to sit while I worked. She immediately shot back: "That's OK, I've invited myself!"