User waypoint sync behavior

This weekend I took a friend and his girlfriend on a "sightseeing" flight. It was actually for him to propose marriage (she said yes!) The plan was for me to fly around the local area and then orbit her house while he popped the question.

The IFD540 had several user waypoints added by my co-owner.

At home, I created a new user waypoint on the IFD100. The IFD100 did not display any of the waypoints defined in the IFD540.

In the plane, I launched the IFD100 app and verified that the new waypoint was visible. I then took off and started my flight.

When I went to the waypoint tab of the FMS page, I saw only the previous IFD540 waypoints. Some time after switching to that page, those waypoints appeared on the IFD100 also, and I lost the new waypoint I had created.

Is this expected behavior-- do waypoints in the panel always override ones on the IFD100? I would have expected a merge between the two. Is it possible to capture the waypoints from the panel in the app and then modify them at home, uploading the changes to the panel, or is the IFD100 waypoint list always updated from the panel when I'm in the plane?