How can I add a usercontrol to a word document?

Globals.ThisDocument.Controls.AddControl(control, range, width, height, controlName)

If I have multiple Word documents open and want to activate a specific one, I can loop through them using the syntax:

'-

Dim WordAppAs Microsoft.Office.Interop.Word.Application

WordApp =CType(System.Runtime.InteropServices.Marshal.GetActiveObject("Word.Application"), Word.Application)

Dim wordDocAs Word.Document

ForEach wordDocIn WordApp.Documents

If wordDoc.Name = desiredDocNameThen

'-

However, once I activate a document using the above syntax, I cannot add a usercontrol to it because the Word.Document object does not have a controls collection. So If I could add a usercontrol using the syntax

Globals.ThisDocument.Controls.AddControl(control, range, width, height, controlName)

then how could I accomplish the same thing with the wordDoc example above. If this is not possible, is it possible to loop through the open documents a different way? Thanks.