Sounds wonderful! I'm glad you got it worked out.

All sorts of ways for families to coordinate on group cruises. One family got inexpensive battery-operated walkie-talkies for everybody. Another simply agreed that everybody gets to go their own way, but they always get together at a specific time for dinner and share the day's adventures. There should be in-room phones, on which voice messages can be left. Door bulletin boards work for some, with messages as to where the occupants might be.

In any case, hope you all have a wonderful time. My parents (and of course grandparents) are long gone, but I have no regrets about doing any shared adventure they every wanted me to do.