File level trustee assignments are lost when saving Microsoft Office documents

Trustees are set on a Microsoft Office document.  When you edit this document and then save it the trustees no longer appear on the file.

This is caused by the way that Microsoft Office does the saving.  It creates a new temporary file and then puts the changes into this file and then renames it to be the original name and deletes the old one.  As this is a new file it will not have any trustee assignments.

Place the file that needs trustees into a new folder, then assign the new folder the appropriate trustee rights.  Then each new file will have the correct rights due to the rights that it inherits from the folder.