Hi Audrey!
Sounds like a fun & Magical, multi-generational trip you've got planned for the future!
You will have no problem dining together at Walt Disney World using different 'payment' methods.
You'll still want to log into the
Disney Dining Reservations system as soon as you hit that Magical 180-day mark from the start of your trip, and begin booking all your wonderful reservations as a party of 8.
Feel free to link the reservations to your Magic Your Way Package as you do so (even though your room reservation is for 6), so that all your information will be stored neatly in one place.
Upon arrival at each of your reservations, a Cast Member at the seating podium will confirm the number in your party, and whether you are on a Disney Dining Plan. You'll simply inform them of the 'split' at that time, as well as with your server when he or she greets you at your table. Since your party is more than 6 guests, you will be charged an automatic 18% gratuity on each of your meals at Table Service Restaurants. Your server will request your Key To The World Card at the end of your meal to run through your dining plan for those of you on the plan, and present a regular Guest Check for payment to your parents.
I hope you'll visit again if there's anything further I can assist you with to make your plans all the more Magical!
Enjoy making all your plans for your upcoming vacation Audrey!
Kirsten