TabWorkspace - Hide Tabs

You can try adding something like this to the MDIChild form:

Private Sub Form_Load()
       
    Top = -200
    Left = -200
    Width = 31000
    Height = 31000
    Form_Resize
   
    fMainForm.DocumentCount = fMainForm.DocumentCount + 1
    ShowTabWorkspace
End Sub

Private Sub Form_Unload(Cancel As Integer)
    fMainForm.DocumentCount = fMainForm.DocumentCount - 1
    ShowTabWorkspace
End Sub

Private Sub ShowTabWorkspace()
    If fMainForm.DocumentCount = 1 Then
        fMainForm.CommandBars.ShowTabWorkspace (False)
    Else
       fMainForm.CommandBars.ShowTabWorkspace (True)
    End If
End Sub

Then add this to the MDI Form:

Public DocumentCount As Long

DocumentCount = 0