You can't at the moment and I have a feeling that it will be a little bit tricky to add support for this. The main reason being that Neo listens to change events to update internal data structures. When you change a foreign key comprising two columns this results in two events being sent with the first one leaving the system in an inconsistent state. You would need to be able to tell the listeners that they should ignore this first event. But what happens when you are genuinely changing the key by only modifying one column. Then the listeners have to react! Smells like lightweight transactions but that's not part of the architecture of ADO.NET.
