Scope and Quality Objectives

We are part of the big organization (our HR, IT, Finance and Marketing) are part of a shared service i.e. they reports to the HQ but they located locally in our facility. My question is, should they be a part our ISO scope? My gut feeling tells me yes since they are impacting customer service. If yes, do Shared Services create their own quality objectives based on their immediate leaders from HQ that is also aligned with our Quality Objectives. Also, how would we required them to do their quality objectives, should our top management discuss this to their bosses in HQ? Note, the HQ and our facility supports different quality policy.