Defining scope and repercussions

We are thinking about certifying our core process – sighttest provided by our stores. Our company has a franchise-structure. Thus each store is its own company. We also have a country support office providing all support processes (eg product, finance, marketing, etc) to our stores. My question is if we can certify the core business provided by the store only, or if we need to include all subprocesses also (of course, it's something we would like to add at least in a second stage). If we then get the ISO 9001:2015 certification, will it then be one per store?
Many thanks for your reply,

Answer:

You can limit the scope of your QMS on only one store only and core processes but in that case, the certificate will apply to this store only since it is assigned to the scope of the QMS. Since every store is a separate legal entity, it is better to certify them all separately, it can cost more in total but it will allow you to go step by step and to create multiple simple systems instead of one complex QMS.

Also, you wont be needing t he consultant help in every store because you can copy the QMS to the similar stores and processes and basically, the only expense will be the certification.