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As we all know, Edward II of England was originally betrothed to Margaret, Maid of Norway, before her death in 1290, and then to a daughter of the Count of Flanders before it was broken up by Philip IV of France. But from reading this blog post by Kathryn Warner, (http://edwardthesecond.blogspot.com.au/2007/06/more-betrothals.html?m=1. Check out the rest of the blog, it's great!), I learned that he was also in 1302 offered the hand of Isabella, elder sister of Ferdinand IV of Castile.
What if the two had actually married? Personally, Edward could still get a French alliance if he marries Margaret/Blanche of France. I'd also recommend checking out the rest of Kathryn Warner's blog.