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So apparently the Spanish and Portuguese liberals had both agreed to give Pedro IV (who was also the emperor of Brazil) the crowns of both Portugal and Spain and give him the title of Emperor of Iberia as a constitutional monarchy in 1830. Yet nothing came of it.
I haven't found much concrete information concerning the accuracy of this conspiracy. Aside from a source in a wikipedia article. But I am expecting to get a book that will hopefully shed light on the subject.