Modding

How can I change the terrain in the creature hiring window if it's in a town?

Here are the maps where creatures and heroes are placed when hiring and viewing:
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Dirt\SmallSpecialArena_Dirt.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Dwarven\map.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Grass\SmallSpecialArena_Grass.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Grass_Beach\SmallSpecialArena_Grass_Beach.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Lava\SmallSpecialArena_Lava.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Sand\SmallSpecialArena_Sand.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Snow\map.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Subterra\SmallSpecialArenas_Subterra.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Sylvan\SmallSpecialArena_Sylvan.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Taiga\map.xdb#xpointer(\AdvMapDesc)
AdvMapDesc \Maps\SmallSpecialArenas\HeroScreenArenas\SmallSpecialArena_Wasteland\map.xdb#xpointer(\AdvMapDesc)