I find Louis Charlin from at least 1904 (in business with famous maker Jean Santiot) to 1963 (Charlin the company) a completely separate company as Darne....also it seems that Charlin, the company, invented the plume barrel in 1949.....

Alexandre Bayle made sliding breech shotguns between the wars, that to my untrained eye, look more like a Charlin than a Darne.