It seems there is a minor bug in the CC.add method. Despite the fact that you can target a specific location to add a CC, if another CC is selected, the method fails:
Sub CCAddBug()
Dim oCC As ContentControl
Dim oRng As Word.Range
'Attempts to insert a CC as an optional range target fails if another CC has the focus (is selected)
'Create three empty paragraphs.
ActiveDocument.Range.Text = vbCr + vbCr
Set oRng = ActiveDocument.Range(0, 0)
'Add CC at oRng.
Set oCC = ActiveDocument.ContentControls.Add(wdContentControlText, oRng)
'Notice oCC.Range is now selected.
Set oRng = ActiveDocument.Paragraphs(2).Range
On Error GoTo err_Debugger
'Since the previous CC is selected an error occurs.
Set oCC = ActiveDocument.ContentControls.Add(wdContentControlText, oRng)
lbl_Exit:
Exit Sub
err_Debugger:
ActiveDocument.Paragraphs(3).Range.Select
Resume
End Sub
Sub CCAddNoError()
Dim oCC As ContentControl
Dim oRng As Word.Range
'Create three empty paragraphs.
ActiveDocument.Range.Text = vbCr + vbCr
Set oRng = ActiveDocument.Paragraphs(1).Range
'Add CC at oRng.
Set oCC = ActiveDocument.ContentControls.Add(wdContentControlText, oRng)
'Notice oCC.Range is "NOT" selected.
Set oRng = ActiveDocument.Paragraphs(2).Range
'Since the previous CC is "NOT" selected there is no error.
Set oCC = ActiveDocument.ContentControls.Add(wdContentControlText, oRng)
lbl_Exit:
Exit Sub
End Sub