If you know how to use Access with Macola and are confident in your skills:
Have users exit Macola
Back up the Macola file.
Use a Make table query in Access to make an exact copy of the Macola file as an Access table. Visually check the Macola file and the Access table to make sure the record counts are exactly the same.
Initialize the Macola file in System manager, which will delete all the data from the file, leaving you with an empty structure.
Make your changes to the Access clone table using Update queries.
When done, do an Append query in Access, using the Access table as the source and the empty Macola table as the target. When finished check record counts.
Test it.
If you have any problems, restore the backup. If you get any errors doing the Append, restore the backup.
If this fails, there are a number of utilities out there you can buy to do the job.