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According to this post from an old thread, Archduke Karl of Teschen was offered the imperial diadem of Mexico shortly after it proclaimed its independence, and King Fernando forbade any of the Spanish infantes to accept the crown. And since the Bourbon-Bragança, Neapolitan and Parmese princes were Fernando's nephews (plus Spanish infantes), whilst his older brothers are Austrian emperor and Tuscan grand duke respectively, Karl is next in line (plus unlikely to inherit either Austria or Tuscany (or anywhere else). So, say Karl accepts the Mexican offer, what happens next?
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