hi
Now lets see if I can get the sequence right -from memory
Etling glass was made by Choisy-Le-Roi -who held all the moulds -in it's later days run By Pierre D'Avesn (ex of Rene Lalique and Daum)
As WWII ended Sevres bought up a number of glass works mostly opalescence specialists (as that's what Sevres had specialised in under their family name 'Landier')
Sevres bought up Choisy-le-Roi leaving D'Avesn in charge of continued production of the many opalescent moulds they had in stock -Etling, Hunebelle, etc etc -These were often signed Sevres -more often unsigned
Pierre D'Avesn was more interested in Sevres' new ventures in Crystal statues
So pieces from companies like Etling appeared signed Sevres in opal and in a (I think demi) crystal
The owners of Sevres liked them and commissioned D'Avesn to design for their Crystal side, which he did very successfully until he died many years later. (My favourite if you've seen it is 'the cyclist')
Sorry long story - no doubt others can correct any inaccuracies
Cheers
Mike