I'm confused. Section 3.1 of the 4th Edition PPAP manual is about customer notification and submission requirements, and I'm not sure how your question relates to it, or to PPAP in general. I don't think that outside operations belong in a control plan, because I believe that control plans should include only those processes which you actually control directly. We should be able to see the routing of material in your process flow diagram, and the possibilities for bad things to happen should be addressed in the
PFMEA, but that doesn't mean that you also have to address them in your control plan. For PPAP purposes, you can include a copies of sub-tier documentation (your suppliers' control plans) but you shouldn't do that unless your customer actually wants to see them.