Kinvara (high-ranking Red Priestess) was in only one scene in Season 6 ("The Door"). The scene was a discussion with Tyrion and Varys about how to calm the civil unrest in Meereen. After that, nothing. There was no more mention directly, or obliquely, of the Red Priestesses (other than Melisandre) in Season 6.
So, what is going on with the Red Priestesses of Volantis? Did the discussion with Varys and Tyrion mean anything? There is so much material to cover in so little time, that could not have been a no-op. So, why have that scene?