It is true. But yes, they can use their cash room inventory, I never said they couldn't.
Their "cash room inventory" = rooms that are undeclared + the rooms that they themselves have booked with their points (with the same reservation booking dates as everyone else booking.)
That means the room you are staying in, if it wasn't in the website for booking when you bought,
WAS bookable by anyone earlier, then
DVC was the one who booked it,
then later offered it for your welcome home stay. You just started your process after it was already booked and in the cash inventory
Any room at a sold out resort has to be bookable by any owners before DVC can book it themselves and use it for a welcome home stay. Otherwise they can use undeclared inventory, and those are
not available for booking yet by members otherwise.
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For more info, I was responding to some talk about DVC maybe being able to book a room that is being walked by other members for a Welcome Home stay. They would not be able to do that because the room will be gone before the 11 month window. If the room is available right at the 11 month window, or in your case if they had already previously booked a room to add it to their cash inventory, then yes they can use those rooms for WH stays