Diaper Change

I just witnessed one of the funniest things I have seen the girls do in a while. The girls were outside playing and I was picking up stuff around the house.
Natalie comes in murmuring something about wet, diaper, poop. I figured she was talking to herself so I did not put much attention. She came in went upstairs and then I see her walking back out the door with one of Izzie's diapers in her hand. Izzie is outside too playing in the sand tables.
So Natalie is now outside in the back porch and even with the door closed I hear her yell to Izzie "Izzie come you have a poop". So now I am curious as to what Natalie is doing, since she is holding a diaper in her hand.
Izzie comes over (not sure why when Natalie calls her she comes but when I call her she ignores me). So I am not sure if Natalie is going to bring Izzie to me or what so I watch what they are doing and next thing I know Izzie is on the floor with her legs up in the air and Natalie is sitting with her taking her shoes off.
Natalie pulls off her pants and takes Izzie's diaper off. At this point Izzie gets up and Natalie realizes that there is no poop in the diaper says "ahh no poop just wet". So now Izzie is running around half naked and Natalie is trying to get her to lay down to put the diaper on. Since I don't think Natalie can put a diaper on I went to help.
I was able to get some pictures but they are from the inside through the windows so they are not very clear. If I would have opened the door they would have stopped.

So as I am writing this, Natalie comes back in the house and is again talking to herself something about again. I watch her come down the stairs with another diaper. She tells me that Izzie's diaper is wet. They are playing in the dog's water dish outside. I tell Natalie don't worry that I will change her diaper and she tells me "no no I will change the diaper". If only she really could change them that would be great!