A bit late for you maybe, but I solved the Gripshi* on front mech problem by rotating it around the bar so the grab was more over the front endiing up less bent wrist if that sounds right. ie rotate the grip over and away from the rider. The limiting factor is brake lever angle, but it makes a massive difference on upshifts. If that had failed I was going Spare LX rapid fire, but not sure if child thumbs were big enough!