Annual pass or not

I am so confused about universals annual pass. We just returned from a trip that I had just booked via universal website. Have another trip in dec but I bought tickets via undercover tourist and just booked universal hotel on Expedia. Have plans to go back again next August.
So wondering first of all can I upgrade my undercover tourist tickets for a annual pass? If I can do I upgrade just myself or my DH and DS too? Also wondering what would be the major benefits of upgrading?

When I was last there in August of last year, I upgraded everyone in my family from Undercover Tourist tickets to seasonal passes. It cost me nothing to upgrade my kids and $10 to upgrade my husband, given the type of tickets that we had. For the life of me, I cannot remember if I got the value that I paid Udercover Tourist or the value that Universal would have charged for the tickets in the first place. I did the upgrade to give us the option to return, given that the cost was so cheap. If we had at least one more trip already in the works, I may have looked into upgrading to a higher annual pass to give us discounts on food and shopping.

In your case, you can upgrade one, two or three people. It doesn’t have to be all or nothing. If you already have a return trip planned, it will probably be cheaper to get everyone annual passes. Whether or not you choose to go with the cheapest seasonal pass or a higher-end pass that gives you discounts will depend on the number of days and the value of those discounts.