Note 3d-tiles-tools has a merge and mergeJson commands (the last one we did a PR for), to result in a master tileset, but these are usually not made for combining too many tilesets since the cesiumjs/3dTilesRendererJs/qgis libraries would do one request per child per tileset at a given viewport, which would lose the benefit of hierarchy of the hlod. Merging the meshes outside of RC (eventually via CLI rather than blender gui), importing to RC componnet and then exporting s 3dtiles might be a better option.