Welcome aboard, Tracy! Congratulations on booking your cruise on the Disney Wonder for next year! Since it's still a ways away, that leaves you plenty of time to research and plan all of the exciting extras that you can experience with Disney Cruise Line!
Edge is the tween club on the Wonder, and it is for tweens ages 11 - 14. Usually, the counselors are happy to allow a child who is almost 11 participate with the tween club with parental permission, especially if they are traveling with a friend or sibling who is in the club. All you need to do is stop by Edge on the first day during Open House hours. You can chat with the counselors there about doing this. Do know that parents do not check their tweens in and out of Edge. They can come and go on their own. Again, just chat with the counselors that first day onboard and your daughters will most likely be able to join their friend in Edge!
If that is the case, be sure all the kids head there for the Ice Breaker activities on that first night. It is then that the counselors plan all sorts of fun "get to know you" activities so that everyone meets each other. It's always easier for kids to join in that night when everyone is new, than to join in later when friendships have already begun to form.
Have fun planning!