ModelMergeSimple_motorway_edition

If you take exactly one model-merge node from the ModelMerge* family, take this one. ModelMergeSimple is the ratio blend - two models in, one ratio, a weighted average out - and it's the closest thing merging has to a single control. This is its Motorway-ed clone: model1 and model2 arrive by key, the merged model is written back by key, and one float decides everything.

How the math works

Merging here means per-weight interpolation between two models, applied as patches on the fly - no new checkpoint file is written. For every weight in model2's diffusion_model, the merged model keeps (1 - ratio) of model1 and takes ratio of model2. So:

• ratio = 0 → you get model1, untouched.
• ratio = 1 → you get model2, which is the default, and it's the gotcha: if you don't move the slider you've built model2, not a blend.
• ratio = 0.5 → a genuine 50/50 average.

This is the node you reach for when you want "Juggernaut's lighting with a hint of that other checkpoint's style" - set the ratio small, sample, nudge. It's also the fastest way to A/B the direction of a merge before committing to a full saved checkpoint. The KB's merge warning is worth keeping in mind: blends "combine strengths of their parents at the cost of some consistency," and the more two models differ, the more a mid-ratio merge tends to flatten both.

The inputs

• INPUT_model1_key (default model1) and INPUT_model2_key (default model2) - the two MODEL keys.
• ratio - the only real knob. Float, 0.0–1.0, step 0.01. Default 1.0 (remember: that's all-model2).
• OUTPUT_MODEL_key (default MODEL) - where the blend lands.

The wrapper keeps ratio as a widget, turns both models into key strings, and keyed-writes the result. Runtime behavior is byte-for-byte the stock ModelMergeSimple.

Install

One install for the whole pack. ComfyUI Manager, search "ComfyUI_agilly1989_motorway", or:

cd ComfyUI/custom_nodes
git clone https://github.com/agilly1989/ComfyUI_agilly1989_motorway

Restart ComfyUI. No requirements.txt, no model downloads.

Troubleshooting

• Merged output that looks exactly like model2 (or model1)? Check ratio - the default is 1.0 and it's easy to forget the slider exists.
• 'MotorwayClass' object has no attribute 'hash_' = a model key isn't in the Motorway; verify the loaders ran and key spelling matches (case-sensitive).
• The two models need the same architecture and ideally the same VAE/CLIP family. Merging SDXL with SD1.5 "works" in the sense that the node runs - it won't produce anything usable.
• Pack caveats: BETA, and the newest published version (1.1.7) disabled clone generation, so on a fresh install these _motorway_edition nodes may be missing from the menu. They're present in the 1.1.0–1.1.6 builds comfy.icu indexed.