If you want to get a good pic of the screamer, the third child, the sweet one...
I suggest that you not ask her directly for a pic.
Instead, begin to take pictures of Dixie
Really get into the picture session too--
camera angles, talking to Dixie and asking her to smile
and try not to even notice when the youngest comes sliding down the bricks
Then she might say something like, What if I stand next to Dixie and you take our picture?
Act a bit surprised and thoughtful and say, Yes, that's a great idea!
She might even forget about the camera for a minute or two and play with her sweet Dixie.
And then, only then will she comfortably let you snap some pics.
Making a face or two for the camera...
You might even get a good smile
A smile worth playing around with a bit
or a classic dramatic pose.
Definitely, definitely, do not say to your youngest, your screamer, your dramatic one:
Oh, I love that dress and boots and hat,
Can I please take your picture?