As long as her 13th birthday falls after the close of the 2004 Worlds (hers obviously does) she can compete as a cub for this last year. As far as shooting together, that does not work at the Worlds, sorry. For the Worlds competition you will be matched up with your peers to shoot. It is really too big and complex of an event to do otherwise. She can be accompanied by an adult if that can be worked out as long as she is not assisted by one. I understand your concern, but mixing classes at this event just does not work. Finally 40# draw weight is the max for cub class. It does not matter what weight the bow is capable of as long as it is not used over 40#. Be careful!!! Cubs have equipment checked at the worlds same as anyone else, and it sucks to have to DQ a kid for equipment infractions.

I hope this helps and I hope you both have a great time on the mountain.