3-upgrade\german\commander\ability\railway_artillery_support (can not find "railway_gun_artillery" )
add "required_player_upgrade" to requirements, set "reason" to "usage_and_display"
but still it does't work.
You need to modify the ability's requirements. Do not touch the upgrade.
The ability is called "abilities\german\modal_ability\commander_ability\railway_gun_artillery".
Its requirements look like this:
required_resource: 12CP
required_player_upgrade: "attributes\upgrade\blizzard_active", is_present: False
required_player_upgrade: "attributes\upgrade\german\commander\ability\railway_artillery_support"
All of these requirements need to be fulfilled for the ability to be available. You need to modify them to look like this:
required_resource: 12CP
required_player_upgrade: "attributes\upgrade\blizzard_active", is_present: False
required_any_in_list
-required_player_upgrade: "attributes\upgrade\german\commander\ability\railway_artillery_support"
-required_all_in_list
--required_player_upgrade: "attributes\upgrade\german\commander\passive\pak_43_emplacement"
--required_player_upgrade: "attributes\upgrade\german\commander\ability\assault_field_officer"