How to train a diffusion model from a starting weights file?

Hello there,

I’ve trained a model that generates trees in the style of RollerCoaster Tycoon.
Here is one example:

I’ve used the dreambooth google collab for this:
DreamBooth_Stable_Diffusion.ipynb - Colaboratory (

Anyway, I’d like to add some concepts to my trained model and I don’t want to start from scratch. Initially I’ve picked runwayml/stable-diffusion-v1-5 for the starting diffusion model. So I created a model:
frutiemax/rct_ai_graphics · Hugging Face

I’ve pushed the weights to the git repository (the 2GB .ckpt file).
I guess I have to change the MODEL_NAME line to frutiemax/rct_ai_graphics but I’m not too sure if this will do the job correctly. Anybody can guide me to the proper documentation, I’m a bit lost I have to admit…

Ps. this is for non-commercial usage and for the OpenRCT2 project.