Knights of Tezoth

There is this point 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 was no alternative.

That is, Maria-Tenerezza and Carnea have more right to the throne, following such practices, than Renavan. And that's 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.

Does such a system still apply after the aristocratic coup? It seemed to me that at some point the lords were appointing their puppets. And did Renavan himself officially designate Koymik as his heir before the pseudo-drowning?