Turn the question around: “can I make a composite into a prototype?” The answer is no. “Can the composited notes have the same or different prototypes?” Yes.
So, you can generate a composite “Apple Pie” whose two notes have prototypes “Fruit” and “Crust”, individually. Then you can make a new instance of the “Apple Pie” composite and one of that instance’s two notes will have the “Fruit” prototype and the other the “Crust” prototype.
So, “can I quickly generate composites from a prototype”. No. But you can quickly add a composite from a previously defined composite. (The “Apple Pie” composite needs to be located in
/Composites, as you know.)
Composites and prototypes are two separate concepts.