Chuck, I think that's been generally true in the past; they source what they can get and bottle it. However, as you may know, the recent trend has been for the bottling companies to buy distilleries which gives them a foothold in the industry and more choices about how to release their whiskey. Signatory now owns Edradour; Gordon & MacPhail owns Benromach, Cadenhead and Springbank have common ownership and Murray McDavid owns Bruichladdich.
If they own an interest in a distillery, wouldn't it be fair to say they are no longer independent? Bruichladdich under a Murray McDavid label is just an alternate expression, not a true independent bottling.