"Fluid" content area inside of a component

I want to be able to have a frame within a component in which the content can change. For example: a modal component with a frame for content:

  • In Design System, a modal component is created. One frame is named ‘content’, set to “Fluid”, and AutoLayout is added.
  • Designer adds modal component to designs.
  • Designer deletes placeholder (empty state) content from the ‘content’ frame.
  • Designer adds new content for modal.
  • New modal design is complete without detaching the component.

Another example is a simple menu, giving a designer the ability to duplicate and reorder menu items without detaching the menu component.