i assume unusual locations would be things like the tilean trading company/ dwarf mines/slaanesh grapevine? no theres no way to currently add these. and it wouldn't work with the BB slot as thats for primary build slots, and BBF for horde build slots, under command works for skaven undercities - but as far as VC/outpost/unusual locations - you cant do it.

Yes, I intended those locations. The bb command works, but only if you have a free building slot. For example in the screenshots you can see a built assassin hideout using this command:
bb wh3_main_minor_cult_assassins_hideout_1.
Given that there's a command for underground structures, It would be useful to have a specific command for those locations

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3451709015

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3451709059

i should amend my statement as there is no way to properly add these. you can add any building via BB command and it would work, including other factions buildings, ports etc. but they tend to just ruin the game as you cant remove them afterwards. but yeah the under command doesnt work, thats only for skaven.