Split & migrate an indexed database

Hi. I am currently switching to a new mac with less disk space, so i wold organize DTP databases in a different way. Now I have some 7 db with both indexed and copied items. I would like to split some of them and create new identical db with copied items: the idea is to bring with me my work in an external drive and copy just the db i need.
A possible way to do it is to sync the db, delete the indexed items in the db and copy the same items from the original folders. Then I will split every single db in smaller ones.
But I cannot find a way to distinguish between indexed and copied items in the db.
Have you any better idea to accomplish this task? How can I distinguish indexed items from copied ones?
Thank you for your support.