These activities you mention are meals provided by the hotel. A very accurate advance count is needed so that they may prepare enough food without waste of either their food or the club's money.
Often there is a very slight excess of food prepared, but it is not guaranteed that more people than expected will be accomodated.
Registration has, in past TDI festivals, been possible for last minute attendees, but there is no assurance of sufficient extra mementos or event souvenirs being available.
Perhaps one of the event comittee members will reply if this year's event can also partially accomodate late registrations.