Here’s what I did:
The new SD card comes as a .pbf file of everything. When you load it, it has all of the song collections and drumkits. Once I had that loaded, before saving my project again, I exported each of the song collections and each of the premium drumkits. Then, I quit BB Manager without saving the project. I restarted with my old project, and each premium drumkit and each song collection that I wanted. Now since I ahve each collection and each drumkit saved independently of the SD card, I can create projects with as little or as much as I want in them on separate SD cards.