That's the beauty of having a closed or secret group -- you can only find out about it through the DIS or if someone brings you in as a friend.
I can scare you more ---- last cruise on the DIS, we has someone pop in and say that their friend was cruising and wanted to join the FE group. Twenty minutes later we got a post from someone making their first post saying they wanted to join the FE, could someone please send them the list.
It seemed strange to us that it would happen so fast with no introductions or participation so we held off. Upon further investigation, we found that the first poster had make about 10+ other posts to other meets saying something similar and those were the only posts they'd ever made on the DIS. Neither ever posted again.
We suspected something strange. Remember that on public boards - especially where you identify yourself, ANYONE can see who you are and when you are going to be away from your house -- especially in a meet group. When FE info is posted on the public board, basically you have no idea who now has the information about you, your kids names and ages and possibly where you live. That's putting a lot of faith in the general populus.
Privacy is a big deal. We are very lucky in that our FE person keeps the information on the DIS board, but only posts info in the private FB group.
I guess it just depends what you prefer.