they should all do, they make up their mind, realize a family isn’t their, wait for them to show up, discuss for another hour what to do, people get grumpy, everyone goes to do something together, half the people leave early and you just wasted half your day.
My advice is don’t worry about doing things together other than a couple of things that were agreed upon prior to the cruise, something like eat dinner together one night (multiple tables) or take a group dancing class. Keep in mind a group that large is hard to accommodate.
The rest of the time enjoy and meet with smaller groups if you want to. Otherwise you will waste half your time standing around trying to figure out what to do or where to be or how to include everyone even though they may not want to be there.