One of my SEO clients has three sites, one for each area of business they cover. However, they are now setting up a new hub site to discuss all areas of their business. The three sites will each be replaced by a landing page on the new site. Now, because the SERs for the three existing sites are very good, they naturally want to keep hold of the old domains rather than make them into a simple redirect. For this reason, they've asked us to make the old three sites display the new landing pages directly from the new site instead of what they have on their front end now. Of course, I'm worried that if we do this for them, they're going to get whomped by Google for duplicate content, and am looking for a way around the problem. I'm leaning towards a REL canonical to tell the spiders to treat this and that as the same thing. Does anyone have any input on the subject?