Marcatis will need to approve a promotion but will generally be very defferential to Provost's recommendation. Vythigor-Shalsad had some very interesting (from RP perspective) Provost-Vindicator tension. At the end of the day, Vythigor could not really boot Shalsad but could certainly do it if he convinced Marcatis.

There is a new system now in place put in by Grobbak (Delad) which Valk (current Provost) follows. But I don't think it effects the ultimate Provost-Justiciar/Vindicator relationship.

I was always a huge opponent of using Seantryn to Galadon "promotion" system. All cities need to be manned. I rewarded seniority by having a "senior Magistrate" head each city. (mini-unofficial-Provincial style).