Will They Got Mad if We Argue Fair Use?

Dear Rich: If we buy half a dozen of photos from a photo agency, let’s call it XYZ images, and discover that other photos which we obtained from out-of-business newspaper archives (sold on eBay) are credited to a Now Defunct News Service (NDNS) a company since bought out by XYZ, are we obligated to declare those additional photos to XYZ? These are photos that otherwise appear to meet the criteria for fair use, and are not found in a search of the XYZ’s website. If we already did report to XYZ that we have some of these pictures, would that void our option to fair use those photos? If we told them our attorney advised fair-using the NDNS photos, would that make them mad or would they consider that normal business practice? You can buy and sell photos on eBay but if you want the right to reproduce those photos, you'll need permission from the copyright owner. Otherwise, if the owner learns of your use and decides to hassle you, you'll have to deal with the infringement or defend yourself with a fair use argument.
Making them mad. We don't know if claiming fair use will make the owner angry. But if you're using fair use as a negotiating tool, be prepared to defend your position with a reasonable argument based on caselaw. Seeking permission does not preclude you from later claiming fair use -- that's what happened in this case.
BTW Dept. We don't think an attorney would advise "fair-using" something. ("Fair use" is not a verb.)