Makes sense but the problem is that you're using words that already have specific meanings in the space, all related to creating one model with multiple functionalities. Merging meaning merging models into one model. Multi modal meaning one llm that handles multiple modes. The term you want is probably agent or framework or chain or something. Basically, what you describe is when it feels like you're only working with one model. What your title says is when you engineer specifically actually only one model, which is a distinct technical challenge.