OpenStreetMap

Aɣmis n h4ck3rm1k3

Yuzen-it-id h4ck3rm1k3 af 19 August 2009 s 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.