OpenStreetMap

dnjownik wužywarja h4ck3rm1k3

Spisany wót h4ck3rm1k3 dnja 19 August 2009 w English Last updated on 22 September 2009.

merge many osm filesinto one.
concat them and then merge.
this will also give the ids new ids.

If you want to merge/extract or other mess with OSM files you can also use Osmosis...
osm.wiki/Osmosis

Thanks, I will look at that. I know osmosis is powerful.