You can do this with Lightroom 4 (and probably earlier versions as well).
- In the Library module, load up all the photos.
- In the Library Filter bar, choose Text.
- Filter by EXIF: searchable fields include Make, Model, and Serial Number of the camera used.
- Highlight the filtered results and add copyright info in the metadata section.
- Repeat for each owner/camera
reference: Find photos using the Library Filter bar
There is a free 30-day trial of Lightroom at the Adobe Web site.