Does anyone know if box expansions will work with GOG downloads?.
It looks like they do :) . I have the old Rainbow Six Gold edition - . including the Eagle Watch expansion disk and managed to install it over the GOG version of Rainbow six.
The setup initiation first hanged for a several minutes, but just as I was about to give up, the installation suddenly started - there were a few pop-up dialogs saying that a file could not be located, while another by the same name was found, but not updated as the contents didn't match.
However, the installation process went ahead and completed sucessfully. Then I started the game via the new Eagle Watch icon. I have so far only played a few minutes of the initial mission(the one with the Buran shuttle), but it appears to be working perfectly :) .
I should perhaps mention that I am running it from an old PC(P4 with XP SP3 and old Nvidia videocard).