If you buy an AP, the AP holder can buy the three-day tickets at a discount (I think it’s 10% for seasonal AP and 15% for the other levels). But that purchase must be done at the gate (so you can’t pre-buy them for your trip), and the discount ends up being less because the gate prices are higher than online or third-party ticket prices.
Another option is to buy discounted tickets for everyone, and upgrade to AP for you when you get there. You would go to guest services, and pay the difference between Universal’s price for your ticket and the cost of the AP you want. This is called price bridging.
Now, if you buy your tickets directly from UO, you both know what you paid, and you’d pay the difference, so no discount. But third party sellers set their own prices, so UO doesn’t know or care what you actually paid; they’re still going to charge you the difference they charge between the ticket you have and the AP you want. So if you go to an authorized third party reseller (
undercover tourist, tickets at work, Costco,
AAA, etc.), and get a multi day ticket that is, say, $40 less than what UO charges for that same ticket, you will keep that $40 savings when you bridge. If you use this option, you’ll want to buy the ticket with the biggest discount (that still costs less than the AP you want because UO doesn’t give refunds), not necessarily the ticket that matches the rest of your family (doesn’t matter if it was for 2 days or 10 because it’s going to become an AP anyway).
This option requires some research because some places will list prices with tax and others without tax (UO’s website is without taxes -to see the price with tax, put the ticket in your cart, and go to checkout for the total). Some sellers will tout the price savings, but compare it to gate price, not the website price which is lower. Also, ticket prices will vary by date. Basically just make sure you’re comparing apples to apples.
UO often offers discounts, and it can be hard to figure out what price you’ll be credited if you buy a bundled discounted ticket and room package. But if you take advantage of a free-day promotion (currently, buy two days, get two days free), you will typically only get the value of the two-day ticket you paid for, not the price of a four-day ticket.