The Use Underground stance requires an army to not have moved that turn in order to assume.

I'm trying to add this requirement to the March stance.

I tried making it cost 100% movement points using wh_main_effect_force_all_campaign_stance_ap_cost, but it turns out this doesnt check for sufficient AP, it removes them. So Adopting March sets AP to 0 and gives 50 back, meaning halved movement on the 1st turn.

wh_main_effect_force_all_campaign_stance_ap_cost_dummy is what Use Underground seems to use for its functionality, but when I apply it to March one can still assume it after moving even though it shows up properly in the tool tip.

Any ideas on how to implement this behavior?

These keys are in effect_bundles_to_effects_junctions_tables by the way.