Currently only "Titles" sets are able to be used in the creation of logical Digital Collections:

https://knowledge.exlibrisgroup.com/Alma/Product_Documentation/010Alma_Online_Help_(English)/040Resource_Management/050Inventory/050Managing_Collections#Adding_a_Logical_Collection

We would like the ability attach logical sets of Citations to digital collections so that as reserves are added/removed, we do not have to delete all the titles and re-perform the search, nor do we want to add/remove one-by-one. This way, our course reserves digital collection will always be up to date every semester, without worrying about whether professors have submitted their reserve requests on time.