Creating Customized Bloom Packs

A suggested feature is in choosing a selection of Shell Books from a particular source collection and create a customized Bloom pack. For instance, in case I have numerous books in my source collection and I only want to make a Bloom pack that contains a few shell books from the collection, it would be nice to be able to select ONLY the books I want to include in the Bloom Pack, instead of creating new source collection for every group of shell books I want to package. I am imagining a scenario where I would like to share different shell books with different people and I have them all in one source collection.