RE: Kids starting on a CARVE99  with kids rig
Your big Starboard Hybrid Formula will not be a good teaching board for a different set of reasons from the Carve 99.
And, while I'm sure you don't want to hear this, you are probably not a fully qualified kids windsurfing instructor.
If your 11 year old has expressed an interest in learning to windsurf (i.e. this is her idea) then the best way to get her started is at a kids camp put on by your local windsurfing association or club.
They should have the right types of boards/rigs and an instructional program that recognizes the special needs of kid sailors.
If learning to windsurf is not your daughter's idea, you will significantly decrease the probability for success if you teach her yourself, or teach her on gear that isn't going to work well for her.
And, you may only get one chance to have her learn and like the sport enough to stick with it.
Your 2.7 m2 kids rig will probably be as much a disaster on the Hybrid Formula as it will on the Carve 99.
The CE of a 2.7 m2 kids rig is practically at the mast, not well behind it like a 7.5 m2-12.5 m2 race sail which the Hybrid formula is designed for.
So, if you decide to do this anyway, make sure you put the mast foot absolutely as far back on the board as possible.
At first, it would be very good to find a big Start board and you go out with her, kneeling on the front of the board.
That's how I work with small kids and it's great. Safe, fun, and there's very little risk.
Take the board out yourself first (whether a Start, the Hybrid Formula, or something else) and you determine whether or not you have the board set up correctly so your daughter can sail across the wind and slightly upwind. If you can't get back to the same place you launched, how can she?
If you could find an older smaller "transition" board, with a center fin or centerboard that would be the cheapest way to get her a board that's going to work well.
Also, try the tether or tow board system I've been using.
Tie a small 3mm or 1/4" line with an 18" piece of 3/8 bungee cord spliced/tied in the middle between the mast foot on the tow board and the nose of the students board. The line needs to be about 5-6 m (15-18 feet) long.
Tell the student that their "job" is to keep slack in the rope.
The instructor, on the tow board, should have a similar sized rig to the students. The object here is not to "tow" the student, but to simply give the instructor some control over the students direction.
Anyway, good luck.
Remember to make this fun and don't push too hard. You may only get one chance at having her enjoy windsurfing, so try to do everything you can to make it a very positive experience.
Hope this helps,