If that kid is playing for me I am most likely putting her on the bench. There is no reason for that if it truly was intentional!!!
I don't want my girls initiating contact, but if Blue isn't calling obstruction, what course of action do you suggest?
A pointed (but respectful) question to ask the umpire:
"Blue, the fielder without the ball and not in the act of fielding a batted ball hindered my runner. Isn't that obstruction?"
Now, if the ump answers along the lines of, "In my judgement, the runner was not impeded by the defender" or "I'm sorry, I didn't see it" then you just have to take it. But if the answer is along the lines of, "Yes, but there was no contact" then your next statement should be, "Blue, we are playing under protest."
If you're denied the right to play under protest, your only course is to play and then take it up the chain. Everyone has a UIC. Ask for a meeting and go from there. UIC's like to know if guys they have working for them aren't doing their jobs correctly. Trust me, when I have made some mistakes out there, my UIC wasn't shy about letting me know - not to berate me, but to correct the problem.
No matter what, though, the answer is NOT to coach your girls to initiate contact.