Attaching Basements

I created a blackmarket pawnshop as part of my mod. I’ve also created a secret basement I want to be attached to that pawnshop 100% of the time. How do I do this?

From what I can see of houses it’s stored in a .cpp so it would need a compile. But there are other buildings with basements, like the original mansions or some of the ‘urban sprawl’ mod buildings. Did they do it in JSON? I’ve been sifting through the JSON and I’m just not understanding how basements are attached to buildings.

I originally thought that (looking at mansions), I just had to change the om_terrain to designate that it was underground on the same tile, but that doesn’t seem to work?

=\ I’m not even sure if everything I just typed will make sense to you, but can anyone help me get my head around this?

After several hours of playing with files, I’ve figured out how to generate a basement beneath a building. The issue was that I was debugging buildings into the game, which apparently doesn’t automatically generate the underground? So basically, I thought it wasn’t working, but it was.

Anyway, I was going to explain it here, for people who googled this topic in the future, but I don’t feel like I’m equipped to give an explanation. I also don’t have the ability to delete the thread, so . . .