It would be great if this could be formalised somehow. Like giving "via" and "source document" footnotes to the story [or perhaps an automated top comment that is visually distinguished as editorial] - if you'd not added this note I'd have missed out as I don't have access to tumblr. But it's more that such metadata gives the reader much more control of how they digest the information.

Gizmodo and Colossal both give "via" info.