Did you purchase the APs online? If so, they should already be linked to your
MDE account. You just need to make sure they are assigned to the right people. You can buy MBs and assign them to people in your MDE account at any time. Or even use old MBs if you have them. Any active MB in your account tied to a person with an AP/ticket will allow access to the entitlements for that person (in this case, park admission via the AP). The AP does not need to have been activated to be able to schedule FPs or link MBs. For example, I purchased APs online in December of last year. I assigned them to myself and my BF in MDE. I already had 6 MBs from previous trips assigned to me in MDE. We received new MBs for our stay in September, which got assigned to us in MDE. We activated those APs at Epcot on day 1 of our September trip. All of my MBs (old and new) worked for park entry and FP use. Your MBs are not linked to your AP per se. Your AP is linked to your MDE account, your MB is linked to your MDE. Either the plastic card or the MB are then used to access the information in your MDE account.