Ple-Sen
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There is a point here that the throne had already been passed first to Koymadzhi, and then to Mariarnelia. Additionally, there is this passage:
The system of succession established by Eidos the Iron gave preference to those relatives of the ruler who were in their prime — thus, the elderly were excluded, and the very young were avoided until there were no alternatives.
That is, Maria-Tenerezza and Carnea have more right to the throne, following such practices, than Renavan. And that is assuming he can somehow prove the truth of his guise. In a setting where even good mages have disguise spells, this could be quite difficult. Especially in the context that the current Renavan is a mage, while the previous one was not known for such talents.