I do not think you will save any money trying to book villas at OKW. My family just returned from a 9 day stay in a two bdrm villa, and while it was lovely, it was expensive. Our base was around $9,000 or so if you remove the park tickets cost. We had FD so that was a bonus.
You want to book 2 and a studio, bringing the cost to over $20000 just for lodging. I woudl look at values for your configuration if the budget will not absorb that amount of money. I will say I tried to price a villa for your dates adn was not able to find availability, but that might have been my search that was off.
OKW is gorgeous and restful, and would offer a wonderful way to gather as a family, but I am not at all sure it will save money.
ETA: I just checked a RO rate for POP for your dates with no tix or meals plan. It was about $819 for two adults, so if you look at that cost and book 5 rooms you are still under $10,000 for lodging. You can buy a lot of meals and tickets for that savings, IMO.
I am not trying to discourage you from booking a DVC unit for your family, but I cannot see it being any kind of savings for your dynamic when you are not willing to share space. My family travels as extended family and we often share space in order to increase our resort level, but we are used to this. If your family needs separate space and you are trying to maximize your budget you really should consider separate rooms altogether.