As ruler I have no estate. I can't take an estate in BR because the stronghold is already under a duchy and thereby I would be below the hierarchy line. I can't secede the stronghold to make it its own duchy because there is no Lord there. Our other Duke cannot appoint me Margrave because I would first need an estate in the stronghold. So because I am the top noble in the hierarchy line I have zero power to decide who reigns BR.
Placeholder, it's the only way. Got a buddy who would accept to get the promotions and then step down for you? Maybe you can reward his troubles with either keeping the region (though not the duchy) or simply a bit of gold.
