It’s a real pain to use correctly, but I think the regional prompter extension to automatic1111 is currently the only way to do that: https://github.com/hako-mikan/sd-webui-regional-prompter

Which is to say, I’ve found ‘just give different prompts to the left and right’ to be ok-ish, but I’ve had real trouble in setting up a complex 2d field of different prompts.

I’m I’m wrong on either front, please someone let me know!