I recommend buying a single home resort to start because there's somewhat of an adjustment period for
DVC. You can think you know how it all works but will find there are little things that strike you differently than anticipated or that you didn't foresee.
Doing splits right away is not advisable, IMO. There's more coordination to moving resorts than we thought there would be, packing for day-of needs as well as packing everything else. For one thing, it disrupted our touring plan more than we thought it would. We've spent 2-3 hours lounging and snoozing in lobbies more than once which is not that cozy.
With children, being roomless could be a nightmare unless they're all old enough you can drop bags for transfer and spend the day in the parks. A little needing to nap could be difficult indeed to accomplish when you might not get into your new villa until somewhat after 4:00, which can happen even at the less busy times of year. And, then, you might be in but no bags as yet.
All the above is why I advise buying the resort you think you want most and staying there to start. If determined to try a split right away, book only a few nights there and then more elsewhere at 7 months rather than buying two resorts immediately.