Howdy Laurie! Great question! I LOVE that you are planning for your 2015 vacation!!!!! I wish I could give you all of the information you are seeking. For now, I can tell you about the current special offers.
The Magic Your Way Package information for 2015 should be available mid-summer 2014. Currently, the dining plan lasts for every night that you are staying in your Disney World resort hotel. However, the park tickets that are part of the packages can only be purchased for a maximum of 10 days at a time and there are guidelines that must be met related to dining and theme park tickets for Magic Your Way Packages.
As the date nears for you to book your vacation, I would suggest that you
contact the Cast Members at Walt Disney World and ask them to provide you guidance regarding the best options for a group your size that would also give you the best value. The offerings are subject to change and given the number of guests as well as the length of your stay, you are better off to wait and ensure you have the current information relevant to your vacation.
What an incredible trip you are going to have!! 3 families, 14 days, MAGICAL!
Have a wonderful time as you continue to plan your vacation and please let me know if you have any further questions.