The girls are to smile, nod and pitch. If she insists on pointing the elbow at the catcher, make it an after thought. The girls may decide that they don't want to pitch, if pushed to do something that hurts their lower back.
It's a little passive aggressive, maybe, but I tend to not want to say or even suggest "You said something wrong." It's just not a great way to start a relationship.
I like the idea of taking video of her pitching, but I think I'll only do that if showing her videos of what I like (Hillhouse, Java, etc etc) doesn't take. First, I think I'm going to just show her some videos/clips of what I've been teaching and see how she responds to it. Maybe will have to show her Hillhouse's explanation of why wrist flicks are dumb.
Humility is the toughest... albeit most valuable... lesson we can learn.
Everyone has eyes to see the truth... few have the courage to voice their humility. Recognize that a "coach" is an authority position... no matter who has the seat... and telling the king or queen to be governed by a peasant is usually met with great resistance because of humility.
Point being, it's less about telling them, it's more about providing them with an opportunity. That's the most we can do at times...
DFP is full of visual evidence... direct them here as a resource and as an opportunity to learn advanced pitching mechanics.