I had hoped to create a module (file1) that I could link up to one of many files (file2)that are structuraly the same (same tables and fields) I added a reference for a test file and did a bunch of design, using the other file's tables in my relationship diagram.

But when I tried to edit the file reference to point to a different file, all the fields on a layout that was based upon one of the external file's tables(with exceptions) showed "". The exception was a global container field from an external table that continues to show the correct data.

Is what i am attempting impossible or am I doing it wrong

I notice it says FIELD missing and not FILE missing. This means the relationship is working.

Were the secondary files all generated from the same original?

Maybe FMP keeps a record of related field identities that are not based on their names.

I did a test. I have posted three files. One is the original external file, one is the file containing the file reference to the external file and the third is an exact copy of the external file. Same records, fields, everything.

If you open the testmodule file you see all the data. But if you edit the File Reference to point to the copy, all the fields in the layout based on the external file show ""

TestModule.zip

Try closing the file and opening it back up again. This works to refresh the references for me.