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Usually, I assume, you tell the creator of the content that the site they are giving the content to must link back to the originating page that content is from.
The alternative is using the canonical tag back to the originating page. But what if the second site wants to use that content as only a portion of the total content of different pages: say, they are getting 3 paragraphs, but it will be mixed in with other content.
The corporate site would ONLY be allowed to iframe my content by referencing URLs on my site that rendered the content without any of my site's navigation.