Hopefully I can clarify slightly (we'll see in a paragraph's time!)...
As an owner/ operator, signing a contract with a Subpart G organisation means that THEY, not you become responsible for the aircraft's airworthiness - it's MA 201 (a) and specifically (e) to look at here. That's is in essence what you're paying for and why there is a contract.
Someone has to ensure the aircraft is maintained in accordance with a maintenance programme. In a 'controlled environment', the G organisation has that responsibility. As the owner/ operator, you can have a say about what goes into the programme but it is the job of the organisation managing the aircraft to ensure all items are covered and the work is done correctly (MA708b)
As an owner/ operator, you can instruct your managing company (the Subpart G organisation) to get maintenance performed anywhere and everywhere, so long as it's done by an appropriately approved organisation (i.e. Subpart F or Part 145) and released in accordance with Subpart H - that's MA 708b again.
There - clear as mud!
