AutoCAD Inventor :: Append Folder Location To Filename?

I am using this code snippet to open an idw.  With this code, the idw has to reside at the same file path as the current document. 

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Sub OpenIDW()
On Error GoTo Oops
Dim oDoc As Document
 Set oDoc = ThisApplication.ActiveDocument  
Dim sFullFileName As String    
sFullFileName = oDoc.FullFileName   
Dim sDrawingName As String   
sDrawingName = Left(sFullFileName, Len(sFullFileName) - 4) & ".idw"        
Dim oDrawDoc As DrawingDocument  
Set oDrawDoc = ThisApplication.Documents.Open(sDrawingName)  
Exit Sub  
Oops:     MsgBox "IDW File could not be found. FileName of IDW must be the same as this file.", vbInformation End Sub
>>>>>>>>>>>>>>>>>

"What if"... my idw is not at the same location, but under a subfolder instead..... like this

Part file c:designsDrawingsJobxxx

Idw file c:designsDrawingsJobxxxIDW

I am sure that this can be done by editing the line "sDrawingName = Left(sFullFileName, Len(sFullFileName) - 4) & ".idw"  " .  Everything I have tried did not work.