Hi,
The site doesn't list marks on silverplate, except for a few makers who happened to produce both silver and silverplate and used the same trademark on both wares. In future the site may expand into silverplate marks, but for now your chances of making a silverplate ID outside of the forum area are very slim.
Regards, Tom
ps. Outside of the forum, you need to have javascript enabled to have the navigation menu appear. If you are unable, or averse to enabling it, halfway down the home page you will find a link to a sitemap that will give you access to all pages. You can also access it ->
http://www.925-1000.com/sitemap.html