KIT33R said..
"The other problem is that she is short so she is struggling with depowering the kite."
Others can give advice on kites but can I suggest a seat harness or Dakine Nitro shorts with built in harness instead of a waist harness purely for the reason that, for short people and assume short arms (myself included), when wearing a waist harness the bar is considerably further away from you and you will be overreaching when it is furthest out. Getting the hook lower makes it more manageable. You can get aftermarket small chickenloops for some kites (Cabrinha).
+1.
Go to a store and try different seat and waist harnesses. Hook yourself in and measure differences in throw length.
This is assuming she isn't already using a seat harness of course...