Placing piece below other one that possesses DNS trait

Is there a way to place – preferably through Trigger Action trait – a piece BELOW another piece which – the latter one – possesses DOES NOT STACK trait? I have Political Control markers that which cannot be moved but flipped. Generally, a unit would move above those markers but sometimes player may want to mark his unit as hidden in the fortress – usually it is being done by placing the unit in question below the PC marker. Is there a way to do it in Vassal?

Restricted Access helps a bit – i.e. I can place the unit below the PC, triggering the DOWN command but the drawback is that the PC itself is selectable which I don’t really want. Any hints?

Got it. I used Game Piece Layers. There are three: Above, PC and Below. Normally, a unit has a Layer (set by a Dynamic Property) set to ‘Above’. There are two commands, however - Hide in Fortress, which modifies the Dynamic Property in question to ‘Below’ and Leave the Fortress which sets it back to ‘Above’. Plus some fun with Restrict Command et voila, it works as I wanted it to.