I see in the mailed renewal form that one has the option to purchase their grandfathered season tickets at the "Regular Price" making them eligible for resale on the secondary market.
I think it has a "required" donation next to that price for that section. I remember seeing an $1100 figure when I was looking at it yesterday.
It's under STEP 2 and the amount is already entered in the Regular Price** box on my app. If you have grandfathered tickets, yet bump the donation amount to that "Regular Price" then your tickets are eligible to be sold on the secondary market by you.