Microsoft Excel has a feature called Shared Workbooks where multiple users can open and modify documents simultaneously.
According to Microsoft:
"Shared Workbooks" is an older feature that allows you to collaborate on a workbook with multiple people. This feature has many limitations, and has been replaced by co-authoring. Excel co-authoring is available in Microsoft 365 Apps Excel desktop client and Excel for the Web.
Symantec File Share Encryption 10.5 and above.
Symantec File Share Encryption offers real-time encryption / decryption of files stored on a secured File Share. File Share encryption happens on a file level where headers are added to each file in order to allow proper authentication of encrypted files.
The Shared Workbook feature incorporates Microsoft Office functionality so that multiple users can open a file, and make simultaneous edits to a file. Using this feature on encrypted files may put the data at risk.
This feature is not supported by File Share Encryption because accessing and editing encrypted files at the same time with the Shared Workbook can cause file corruption. Therefore using this functionality is done at the user's own risk.
Symantec Enterprise Division is committed to product quality and satisfied customers. Technical Support filed a Feature Request to add the functionality listed above. This Feature Request is currently being considered by Symantec Enterprise Division to be addressed in a forthcoming version of the product.
There is no guaranteed date for this request from the Encryption Product Management team, or the Encryption Engineering team at this time. Please be sure to refer back to this article periodically as any changes to the status of the request will be reflected here. You can also submit a new ticket to Enterprise Support to receive a direct update from our team or to have your organization added to the list of customers that want this Feature Request.