GetAsText ( ContainerField )
Will return the text found in the container field. This text will include the file name of the inserted file. You should be able to set up a calculation that extracts that filename into a text field using Replace Field Contents.
Then you can use Import Records | Folder to do a batch import into a new table and link it by filename to the records in your original table. You can stay with the related table or use a script with set field to copy the data from the container field in the related record back into the original.
This works as expected, at least up until the part using Replace Field Contents, but that part is simple.
Thanks very much.