The thing is Andi that it wants not only the IGS but EVERY other dependency, even though I'm trying to make it only export the one blueprint, not everything else it wants - the Export This function. Used to work fine...
In your case, I would create all these required blueprints. They can be absolute bogus. Just be sure you backup the original assets as they might get overwritten by the bogus. BUT: (after a backup), if you "touch" the asset files, i.e., if you set their modification date to something newer that the blueprint files, the BE should see that they are up to date and refrain from overwriting. To "touch" a file, serz the .bin and then the .xml. This gets a brand new .bin file that is identical to what it was before, but dated right now.