[quote=@Dead Cruiser]
<Snipped quote by The Nexerus>

I figure at least that her family would know of the Raven-Eye merchant house, if not the pirate known as Blackbird.
[/quote]

Elayne lived in Skyrim for several years, and during the period Blackbird and those like him were operating. It would make sense that she'd have heard of him before.