Business ProfileforPremera Blue Cross

I'm double insured by 2 health insurances, they're Regence and Anthem. I've been always covered under my Dad's Anthem, and for Regence- that's the confusing part: from 2021-2024, I sometimes covered by my mom's plan from Regence and she's the policy holder, and some other time I was covered by Regence when I was the policy holder. (Same insurance same plan, but different policy holders in different period of times during these years)As you may know the following conditions determine who's the primary insurance:1. If you are the policyholder, then that insurance will be your primary insurance. 2. If both of your insurance are under each of your parents, then whoever's birthday comes first will be the primary insurance. That being said, when I'm covered by both my parent's insurance, whoever's birthday first should be my primary insurance, and should pay the medical bills first, whatever amount left will be paid by the secondary insurance. The tricky part is, me and my mom work at the same school district and we chose the same medical insurance plan, unfortunately my employment status changed few times in last couple years, resulted into some period of the time in the year, I was the policy holder, and some period of the time in the year, I was covered by my mom's insurance. Now, I have been receiving medical bills range from 2021 - 2024, those are supposed to pay by Anthem first, because they were the primary insurance at those period of time.But they refused to pay the bills says they weren't the primary insurance at that time.We called Anthem multiple times to explain the situation, and even connected the calls with Regence agents few times, to clarify the time frames of when I was the policy holder and when I was not. Anthem's agent always said "I understand the situation and I will help you with this", but each time we called, few weeks later same situation happened again. We even received bills from collections because Anthem are not paying the bills.