We too just returned from the Zuiderdam 8/30 sailing, had a wonderful time. Get to the Cruise Director early in the week and ask her to set up a FOD meeting. There were over 20 family on our sailing, plus lots of the entertainers and staff, a couple even came to our FOD meeting.
Been busy so haven't checked this. Anyway, have the cruise director list a location for "Friends of Dorothy", and you may have some family show up. I've been on 20 or so cruises but not this line, so am looking forward to it.