Yes, guilty as charged, I do teach law school.
In S.D?
I'm not totally certain that the 13/12 month rule was a "change." As I understand it, that language is contained in at least some of the contracts going way back. But, even if it weren't, my guess is that Marriott would have figured that 50% of the available units would not raise too much of a stink. But, the bottom line is that I don't think Marriott is free to change the reservation process so drastically as to basically gut the value of what was purchased.
At least as to my resort, Shadow Ridge, the reservation rules (12/13 month) are specifically set forth in the deeded documents. The rules are concise and specific.
Notably, there is no distinction between an original purchaser and resale purchaser in those docs. Marriott cannot change any terms of the deed, CC&Rs and Timeshare declaration. In fact, Marriott is simply a manager for the respective HOAs which actually owes the obligations to owners. Simply put Mariott cannot change the "rules" (actually deeded usage rights) for reserving, or using your week, because they are deeded entitlements.
Under CA law, no "rule," changed or not, can supercede or contradict the declarations. In any conflict between a rule and the declarations, the declarations prevail. The Declaration sets forth in detail how reservations can be made. Either you own two weeks, or you fall under the 12 month rule.
Rights to reserve your use week.
(The following is paraphrased from the recorded Shadow Ridge Timeshare Declaration.)
"Timeshare Interest" is defined as the interest in the timeshare condominium referenced in the respective Timeshare Declaration for the resort. [paras. 1.85 and 1.87]
Reserving
Owners who own more than one "Timeshare Interest" may reserve use weeks 13 mos. in advance of (down to 75 days before) the use week reserved, only if they reserve such weeks concurrently or consecutively. [para. 2.1-d-i]
Owners other than above may reserve use weeks 12 mos in advance of (down to 75 days before) the use week reserved. [para. 2.1-d-ii]
[remaining provision relates to reserving within 75 days.]
These provisions are obviously the most material part of a timeshare owner's rights with respect to the property. I can see no conceivable way the substantive rights granted by the Timeshare Declaration could be unilaterally altered by Marriott or its affiliated companies, high priced lawyers or not.
Within any timeshare project, whether it be Marriott or others, the rules apply as they do in any condominium project governed by CC&Rs. Here, the CC&Rs state that only those owners who have 2 or more weeks can (
and have a right to) reserve 13 mos. out and the Association/Marriott must follow those declarations in allowing reservations.
Importantly, "Owner" is defined as any owner of a timeshare interest deed, or
any successor purchaser (RESALE PURCHASER, see para 1.61.) As such, resale buyers are entitled to the same deeded rights of an original purchaser no matter what price was paid. This is no different than neighbors in a condo complex that paid drastically different prices for their unit twenty years apart.
As to Marriott's new program...
No resale buyer has a right to be a part of any new exchange program, etc., or any particular priority.
Obviously, timeshare ownership and the legalities surrounding them are complicated. I enjoy these discussions because they relate to all the promises and lay-opinion given by the salespepople, and put all their simple, strightforward explanations in a more complex context. The more info people have, the better, which I understand the primary purpose of TUGBBS to be.
I implore everyone to keep the distinction between your rights to reserve (deeded) vs. any new points/ exchange program (which can have any rules they want and you agree to when signing up).
P.S. Big companies make big mistakes all of the time. That's what keeps high priced lawyers high priced . . .
NO CHARGE... 
