If you want the
DDP, Disney requires you to purchase tickets along with the DDP as a package. The only reservations that can buy the DDP without park tickets are for people with annual passes or reservations at Disney Vacation Club resorts booked with
DVC points. So, if you split stay with the DDP you would be required to buy tickets with each reservation which will nearly double the cost of your tickets since Disney gives a big discount on additional days past the third day.