There can only be one reference set assigned on one component. However, there is a workaround. 1. Add the component to the drawing twice (once for each reference set you want to use) 2. Set the 1st instance to 'model' ref set and the 2nd instance to 'alternative' 3. Create your drawing views, use 'hide component', visible in the view, or view-dependent edits to hide one or the other representation in the appropriate views 4. If there is a parts list involved, set one of the components to 'ignore' so it doesn't affect the parts count