You'll need to identify and associate the sets of parts. A simple solution would be to assign a common instance variable to each set, so that you can use it to pick the relevant parts in your events.
You can absolutely spawn parts at runtime. Just on start of layouts or whenever, for each body, spawn parts. Containers I think would not be as suitable since you need multiple instances of just one part. Hierarchies might be more applicable, but I'm not familiar with them.