Hi, just to make sure we are talking about the same thing - you mean this following seats:
They are also known as "Sportsitze" and pretty rare in a 7-Series.
Most of them are equipped with the "Komfortsitze" (here Alpina version, only difference are the stripes):
The "Kontursitze" from the E39 should also fit but I am not finally sure about that.
About exchange from "normal" to "Doppelverglasung": there was a thread about this topic a couple of month ago but I cannot remember the outcome. Maybe you will find it through the "Suchen"-option.