Horrific coordination of benefits situation, need advice [Kansas, Virginia]

Anthem BCBS is going back and denying hundreds of claims ($153k worth) that they previously approved and paid from 03/01/2021 to 12/31/2022 because their system updated on 10/28/2022 to show that Kaiser Permanente has been my primary insurance since 03/01/2021. I had no idea I had the Kaiser insurance and neither did my step-mom (the Kaiser coverage is through her employer and the Anthem coverage is through my dad’s employer) but apparently it’s true. I spent all day calling providers to ask them to submit claims to Kaiser and then resubmit to Anthem BCBS with the Kaiser EOBs, with the understanding that because Kaiser only covers emergency services outside of their network and there are no Kaiser providers in Kansas, most of the claims will be denied by them and can be paid by Anthem afterwards. Most of the providers were willing to do so, but I’ve run into 2 so far that absolutely refused and suggested I submit my own claims to Kaiser. Kaiser will only allow me to submit a claim directly if I pay out of pocket and request reimbursement. Just the claims from these 2 providers would be $928 if I did that, and I haven’t even finished going through the list of 37 providers yet. One of the 2 also refused to update my name to give me a bill with my current legal name on it, with the explanation that they “can’t legally change the name on my medical record” even though medical billing is not the same as my medical record and I’d already updated the name with 5 other providers today as part of the billing process. I managed to disenroll from Kaiser effective 01/01/2023 so it won’t affect future claims but this is such a huge mess. Does anyone have any advice?