Since you've already proven that you cannot follow directions well, you decide to go ahead and ignore Sarah again. You go and sit next to her on the ground, trying not to stare as she sits in just a shirt and her diaper.
You wrap your arm around her and sit for a few minutes, trying to figure out what to do next. Should you apologize? Try to break the ice with some humor? Sit in silence and wait for her to take the lead? This is not a situation you were prepared for, and there seems to be no easy way to move forward.