WI:A Blois restoration after the death of Arthur Duke of Brittany

I was thinking is it possible for Eleanor of Brittany to marry her half cousins from the Blois Family, Theobald of Blois comes to mind, he can marry her instead of his OTL Bride, the heiress to Navarre, this unites the Blois and Plantagenet succession and will be just like Henry Tudor and Elisabeth of York, what would be the consequences of this marriage.
 
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