Quick Migration between maps?

Hi folks,

I am trying to combine past work I've done on a few different maps into one single map. However, using the regular 'import' feature will wipe out what I've already done for the map.

Apart from switching windows and copying one item, ability, etc. at a time, is there any way to speed up migration of custom things?

Copy them to the campaign editor from one map, then back in on the other. Saves switching between maps.