As long as you buy a package, you can add the dining plan to it. However you cannot use your AP to book the package and get a discount rate. If you're going the dining plan route, you can either book the package with 1-day MYW base and use your APs instead for the tickets and save the MYW ticket for next time.
Another route is just to go DDE. You have to make the calculations to see which is more beneficial, AP discount rate + DDE with 20% off or Dining Plan at $35/person/day + tickets + rack rate.