I think I understand your request...
VB Code:
  1. If ((UserForm1.Checkbox1.Value = True) AND (UserForm1.Checkbox2.Value = True)) OR (UserForm1.Checkbox3.Value = True) Then
  2.     'Either both the first two are checked OR just the third one
  3. End If
  4.  
  5. If (UserForm1.Checkbox1.Value = True) AND (UserForm1.Checkbox2.Value = True) AND (UserForm1.Checkbox3.Value = True) Then
  6.     'All three are checked
  7. End If