Running two models when simulating

Is there any way to specify two models to be launched when running the simulator within the Designer? I am developing a frontend application and this frontend needs a backend for many of its tasks to make sense. I have implemented a simple backend in Storyboard, and I would like this backend to always launch when I start the frontend simulation. Is this possible? The documentation says (Multi-File Application Development – Crank Software)

“The Storyboard simulation configuration dialog, accessed via Run > Storyboard Simulator Configurations allows multiple model files to be specified. All models in the 'Selected Models' block will be included in the application when launched.”

…but I cannot find the “Selected Models” block anywhere in that dialog (see screenshot below)