Grady

[winter ore]

You'll want to talk to support (https://support.stripe.com/contact) about the service costs/how it affects your negotiated rate, but I can speak to your first question about migration

How you migrate will depend on how your accounts are set up - if you create this new sub account and connect it to your existing base account then you have the ability to "clone" these customers to your connected account (https://stripe.com/docs/connect/cloning-customers-across-accounts)

The ID will not be persisted to the new Customer object, but it'll save you the trouble of having to recollect their card information