Visual Basic: triggering event when any 2 of a group of checkboxes is checked

I'm trying to program an app to demonstrate the rules of inference and equivalence in proofs in logic, and as part of it, I want to enable buttons that perform 2-premise rules only when two checkboxes are checked. Now, I won't know how many checkboxes there are, because you can add lines (which involves adding a checkbox, textbox and label combination each time). So basically: I have n checkboxes and I want an event triggered when any 2 of them are checked, but those two are non-specific. Help?