I'm a developer working with a client that is having an issue with addresses in the checkout flow not getting saved. When changes are made to an already-existing address (IE an address that was added before the the checkout started), during the checkout process, those changes are not being saved when the checkout is completed. This is causing problems because a large number of customers, because we have made some fields, for instance "phone" mandatory, and the phone previously was not being displayed at all. None of the old addresses have a phone, and so the fact that the change to add a phone during checkout for previously entered addresses isn't saved is slowing down the checkout process.
Is there any AJAX hook that I haven't seen in the documentation or other method which could be used to "force" changes to one of these addresses to be saved?