Maybe i'm understanding you incorrectly but because of inflated numbers your guesstimate is that there are 9.000 less memberships now than compared to may 2014 ?
I fixed a typo that changed my math.
That said, the same inflation existed then, too. If you apply the same guess of 5% inflation (double counted members/memberships, like me), then May '14 would estimate to be:
180,000 vs about 20,000 more memberships over the past few years.
180,000 May'14 vs 199,000 Nov'16
Both the 20K increase and 5% double count are guesses, but I think they're reasonable ones. I think the true count is closer to those adjustments than not accounting for known probable variances.
For example, the period between those two dates includes all the sales at Poly through 11/'16. And the 11/'16 report shows 25K Poly members, and I think the ratio of .67/1 memberships vs members is reasonable, so Poly alone would account for almost 17,000 new memberships.
I'm less sure about making assumptions about number of members. You'd certainly have a decent percentage of single owners, but you'd also have a decent percentage of memberships with adult kids on the deeds, > 2 owners. I don't know how well those two pools offset.
Based on these numbers, DVC has about 200,000 unique contracts that includes more than 300,000 unique members. My best guess is the 200K memberships is fairly close to accurate while the number of total members is less precise. I'd be surprised if DVC had 250K unique memberships, but not surprised if I found out they had north if 350K unique members.