Phillip:
Thanks for the question!
Unfortunately, the Disney Dining Plan isn't that flexible...once you decide on a plan, whether it's the Quick-Service, Basic, or Deluxe, you'll have to stay with that plan for your entire vacation package.
I hesitate to mention it, but there is a loophole: you can make two separate vacation packages for your stay, say a 3-night and a 4-night, each one with the different dining plans. However, the price of the tickets in each package may make not make it worth your efforts because you do have to purchase at least a one-day theme park ticket with each package. And with this plan, not only might you may have to change rooms but Disney's best vacation deals come with the longer stays...not ideal, and certainly not worth the flexibility of having two different dining plans...
You didn't mention why you wanted to split, but if the Basic Plan with one table service, one counter service and one snack busts your budget, consider getting the Quick Service Plan and then paying for one table service meal out of pocket. OR if you're concerned that the Basic Plan has too much food for your family (it is PLENTY), you might want to double up one or two of your table service credits for a
dinner show like the
Hoop Dee Doo Revue or a Signature Restaurant like
California Grill.
If you have any more Disney dining question, please feel free to come back to my bio page! I'd be happy to help you navigate their maze of wonderful restaurants!
Whitney