Hi, Cathy!
Wow - a group of 23! That will certainly make for some really fun group photos! You might want to look into purchasing
Memory Maker. This will be the perfect way to capture your vacation and get pictures of your entire gang. If you all split the cost, it will be very reasonable and it will be awesome to have those digital downloads.
As far as your reservation goes, I'm guessing you had a travel agent book your vacation. If so, you will need to go through him/her to modify your reservation to include the
Disney dining plan. Remember, to include the dining plan you need to have a
resort package that includes your resort stay and theme park tickets. All guests staying in your resort room need to be on the same package. If you only want your kids on the plan, not yourself, then it cannot be added.
If the "someone else" who made your reservation was simply a friend and you have control of your reservation, call a friendly cast member at (407)934-7639 to see if the Disney dining plan can be added and what the added cost would be. All modifications need to be made at least 3 days prior to arrival to allow time to process the changes.
Wishing your super-sized group of friends and family a magical stay in Walt Disney World!
Cathy