My understanding is the same as PP. We had to r/s a cruise and were waiting to see Holidays for 2018. Then I realized DD would be 18 and couldn't participate in the Vibe. Since she would be a very young (3 weeks and still in high school) 18, felt she might not feel as comfortable in the 18-20 group. So...we dropped her from the ressie and are sailing in May (but shh...haven't told her that!).