We also have a similar situation with a ledger system used for the first 15 years of our institution’s life. Donations, sometimes in batches and sometimes listed individually, were assigned the next available consecutive number in the ledger. I am working to assign unique object ID #s by adding .001, .002, etc to the original ledger entry for batches of items. Items that stand alone (only one object listed in the ledger entry) keep thier original number with no added prefix. This is working well when I run across the “next item”. I just add the .003 or whatever to the mark, create an accurate record in the collection management database and go on. As I work with the ledger I am able to spot repeat donors and am grouping them into Master Accession records in the CMS to aid in research and donor identification when people inquire about their family items they think were donated in this time period. Sounds like that is pretty much on track with what our colleagues are doing.