You can try the webservice from OSM user Wambacher: [https://osm.wno-edv-service.de/boundaries/][1] https://wambachers-osm.website/boundaries/ and try the "Union" feature at the bottom of the screen after selecting some boundary elements from the tree structure on the left. Then try to export in the format you need. [1]: https://osm.wno-edv-service.de/boundaries/

You can try the webservice from OSM user Wambacher: [https://osm.wno-edv-service.de/boundaries/][1] and try the "Union" feature at the bottom of the screen after selecting some boundary elements from the tree structure on the left. Then try to export in the format you need. [1]: https://osm.wno-edv-service.de/boundaries/