I regularly have a requirement to obtain multiple digital signatures on a Word 2010 docx file. The document is prepared by the author with Insert->Signature Line for each signatory before any of the signatures is applied.
If all signatories access the document from a shared network drive then they can sign without removing any earlier signatures. This reliably works.
However, in circumstances where not all signatories can access a common drive, the document is emailed from signatory to signatory. In this case the addition of multiple signatures sometimes fails. The signatory opens the document and goes to sign it, only to be told that signing the document will remove all earlier signatures.
Is there a setting in Word itself or within the document that is treating the signature as an edit and not as a signature? I can see no pattern in the incidence of failure of this process but can't believe that it is random. It is occurring on both Windows 7 and XP.
The issue is not the same as in earlier questions such as Merge multiple digitally signed versions of Word 2010 document and we cannot use a workflow like http://office.microsoft.com/en-us/help/collect-signatures-in-a-document-by-using-a-workflow-HA010220202.aspx as we don't have a Sharepoint server.