This is something you need to negotiate with your agent when you booked. If you haven't been promised any amenities or discounts before now, you may be out of luck.
Depending on the circumstances you could have offered everyone a better price, by splitting up the value of tour conductor berths, or had a free cocktail party for everyone, or champagne etc in everyone's cabins. You HAD options when booking... I'm afraid now you may be too late!
Kuki is right this should have been negotiated with the TA you booked through. If you just booked as individuals for the 13 rooms you will probably not get anything extra. If you booked the 13 rooms as a group rate your TA should have told you of some possible options which they may not know for sure what those are until final payment is made.
All perks for groups are based on the number of bookings so they can very and in some cases the group would decide what to do with the options that are presented.
Contact your TA and discuss how you were booked and than go from there.
Good Deb. Keep working with your TA and pushing for these perks in writing. Carnival is very good about group business. The usual perks are for every 8 cabins at double occupancy = 16 people, you get one berth free or the equivalent of the average cost when different category cabins are booked. For 16 cabins= 32 people, you get one cabin free or the equivalent cruise only cost less port fees and taxes. Usually you get a 1 hr. well drink open bar cocktail party with snacks - pretzels, chips, etc. at a time designated by the cruise line. Champagne or wine and chocolate covered strawberries may also be given in each cabin. The larger the group, the more perks.
I always cruise with a group. My TA gives the group leader a choice for the group 1) a shared cocktail party for one or two hours or 2) chocolates and a bottle of dry champangne. Last year we had the cocktail party and was able to order mixed drink of our choice. You get one free berth per every eighth person - 3rd and 4th person doesn't apply. You will be responsible for any gov. taxes and fees.