You can combine quads of 2 models, if you create a custom IBakedModel .   First, create 2 model jsons - main one for fluid (should be the one loaded by mc) and one for other things. Subscribe to ModelBakeEvent , retrieve fluid base model from registry with resource location. Now load your second model (with carpets, blanks and stuff). Then you take these 2 models and pass them to your own IBakedModel . In your custom model, implement methods by redirecting to one of models. As for