I asked SDC about BAF pass upgrades to season passes.
Free BAF Passes CAN NOT be upgraded to season passes.
Paid BAF Passes CAN be upgraded to season passes.
Thanks for contacting the park and getting the official word on that. I've been out of town at youth camp the last week and had little to no access to a phone or internet so I knew I wasn't going to be able to do it.
I am pretty sure the "rule" in the past was......
Upgrade on any "paid" ticket...
Which is why I am surprised that the free passes for teachers this month is upgradable..??...?/
As I mentioned, that's not a hard and fast rule. The free admission tickets that employees get that they can give out can be upgraded to annual passes, and that's been true since before I worked at the park, so that has been in place a long time. I know that other free tickets that the park has given out as promotional tickets have also been upgradeable to passes. For example some tickets that were given free to our schools to use as fund raisers or incentives were upgradeable (I know several families who have used those for that purpose), and others given to people to attend a promotional event. Additionally, I get a few free tickets each year for my volunteer work at our local school that I can use or give to friends, and they are also upgradeable.
So the BAF free tickets not being able to be upgraded to passes are the rare exception to the rule.