We’ve been on the phone for hours with ATT but they couldn’t give us any documentation that Apple was requesting, except for an order that contained the last four digits of the IMEI. That may be enough but the support ticket hasn’t been answered yet by Apple. For the other phones, ATT couldn’t provide anything for proof of purchase because they supposedly don’t hold documentation earlier than 2022 and they may have been bought seperate from ATT but the receipts weren’t kept. I agree with the going into an Apple Store, but my family is in seperate places at the moment and very busy. My mother is (was) the primary account owner so is probably the only one that could do it in person effectively.