How much does your daughter weigh?
I would suggest she try the Kod 113 and the Carve 111.
Does the rental shop have any smaller boards?
If she weighs what a normal 9 year old girl weighs, a board in the
85-100 liter range should work even better and can be her high wind
board when she grows a bit.
Look for 2.5 and 3.3 m2 Sailworks Retro Ripper sails.
Lots of power to get her planing, but just as light (maybe lighter) and easy tho handle/
uphaul as the 3.0 Kids rig.
If she wants to plane, can you remove the fixed center fin?
Center fins and planing are normally not terribly compatible.
Too much drag to get planing, to many control problems if she actually
does get planing.