Currently if you choose to manually enter a number for a particular Memory Location / Marker that currently exists, you get a dialog "Are you sure you want to replace the configuration in slot XX? This cannot be undone." It would be great if you provided an option to move the existing marker to a new slot rather than blowing it away.
As it stands now, once I realize that I may erase another marker I have to cancel, cancel again, find the old marker, double-click, re-number the old marker. re-locate where I want the new marker, then make the new marker (again).