Are any of these stays on DVC points? You have two DVC resorts in there.
For stays on points, you can just add the dining plan to those reservations, they don't have to be packages. If they're your points, call Member Services and add it. If they're rented, have the member you're renting from call Member Services and add it. No ticket purchase is required.
For the Pop Century stay, you'd have to book it as a package and buy at least a one-day park ticket for everybody - unless of course you can book the annual passholder package.
Elaborating on what Faldred said, your dining credits for each stay expire at midnight on the checkout day. On the day you check out of BWV and into Pop, you will have to use up any unused credits from the BWV stay before midnight - but you will also acquire all the credits for the Pop Century stay as soon as you check in there. Same thing for checking out of Pop and into BLT.
