Update to Excel 2013 causing a problem with Sage 500 ERP import feature

Question

I work in an accounting office that relies heavily on importing data from Excel into Sage 500 ERP accounting software.  We recently began updating from Office 2007 to Office 2013.  Now we are running into a
huge hurdle as we find Excel 2013 no longer supports MDI, and has moved exclusively to SDI.  This is a problem for us, and here's why.
Sage 500 has a "Data Porter" command which launches Excel, but opens a blank workbook in Excel.  After triggering the Data Porter, we open a previously saved Excel workbook containing our data, select the "Add-Ins"
tab, and click the appropriate button to begin the import.  In Excel 2007 this works because the workbook with the data opens in the same "window" as the blank workbook.
In Excel 2013, the workbook containing the data can only be opened in it's own new window which has not established the line of communication with Sage 500's Data Porter, and the import function is not available.
So far the only workaround we have found is to right-click on a tab in the file containing the data, click "Select All Sheets," then "Move or Copy" them to the new blank workbook.  The import into Sage 500 is successful when
we do that.  However, we need to save the workbook with the updated import information returned by Sage 500, so we must also do a "Save As" for the new workbook, assigning the same file name as the original data file, overwriting
it.  This makes what used to be a simple procedure quite cumbersome, and we fear the risk of data loss may be significant.
Is there any way to make this process work the way it does in earlier versions of Excel that support MDI (Multiple Document Interface)?

Answer 1

Is there any way to make this process work the way it does in earlier versions of Excel that support MDI (Multiple Document Interface)?
At a glance, it seems the answer might be...No.
Note                  
There is no MDI compatibility option in Excel 2013.
From: http://msdn.microsoft.com/en-us/library/office/dn251093.aspx
You should contact Sage, to see if they have solutions/suggestions, but I think it will require Sage to re-develop the Dataporter Add-in ?
Don
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