A customer wants to change from local pickup to shipping

I cannot seem to find a way to change the customer’s order from local pick up to shipping, as they have now requested this. Please can you tell me how to do this, and if it’s not possible, why not?

your customer can change local pickup to shipping From the Shopify app, tap Store > Settings > Shipping and delivery . Scroll to Local delivery and tap Manage next to the location where you want to offer local delivery.

Thanks although I am not sure that will work, we have quite a complex(ish) app running our shipping prices via an app, which varies its prices depending on items and so forth. Or do you mean to do it as a one-off. Not sure why it’s not in the editing function like adding another item etc, which then just invoices the customer.