I have been directed to not use this database to track exhibits
That is a very odd and very unfortunate directive. Any time that the end user starts telling the developer how to design the database (instead of focusing only on what the database will do for them), things get difficult as they often do not understand what they are telling you to do.
"Do I put this data into separate tables or all in one big table" is one of important database design questions for which there often is no hard and fast rule to tell you which option to use. What you can do falls on a spectrum of choices with two extemes: 1 extreme is all separate tables like you have here. The other extreme is one big table with fields that are left empty when not relevant to a particular record in the table The more the data in each table is the same, the stronger the argument for putting it all in one table. The more each table stores data that is different, the more it makes sense to use different tables for each.
But usually the best answer is somewhere in between. You set up a single unified table for all items where you set up fields for each field that is needed for every item in your collection, at least a catalog number and a description field, but you may have others such as a date received or a location field and then you link in your current tables as "detail" records that link to a primary key ( which may not be your catalog number) in the unified table.
Thank you for your response! I've been thinking that the unified table route was the way to go and it is good to get verification of that. Have you, or anyone else for that matter, thoughts on complex, auto generating numbering systems in Filemaker?
My thoughts are not to use them except as a "label" to be displayed on a computer screen or to print out and attach to the item. Do not, under any circumstances, use such a field as the primary key to link one table to another. Stick with an auto-entered serial number or Get ( UUID ) in an auto-enter calculation as the way to link your unified table of items to other tables in your database.