I think not all licensees from Bentglass are listed under glass makers, as technically speaking they are glass refineries printing on slumped float. Nearly all larger countries had a licensee, some were glass industries, others were not - Chance for instance was a glass maker in his own right, Flamingo in Holland only operated the bentglass machines.
I don't think either Charlottenhütte or Christinenhütte would be flattered to be associated with this process.