The current history list can be loaded by choosing "Load history..." from the "File" menu:
Only one data adapter is available for loading OBO-Edit histories: the "OBO-Edit XML History Adapter". A load file is specified using the procedure described in The Basic Flat File Interface.
When a history file is loaded, the edits are applied to the currently loaded ontology. This can be used to merge edits from two users who are working on the same ontology simultaneously.