dickbaker - 11:38 pm on May 22, 2011 (gmt 0)

Thanks for the reply, Andrew. It looks as though I'm going to have to have two sites with different content for each of the products, and let the new one grow on its own.

I'm still trying to find out how Google Shopping/Merchant/Whatever treats noindex tags. If I can keep my current individual product pages with their good Merchant rankings and customer reviews, but 301 redirect the main brand pages to the new site, I may be able to make growing the new site easier.