How do you handle issues with insurance claims when you have 2 employer-sponsored health insurances as the policy holder?

Hi there, I am unfortunately learning as I go here and could use some help. I have two full time jobs in MI that both offer health insurance, I have chosen to take both insurances due to needing to place my husband on insurance but not affording to put him on the nicer plan.

I’ve since had issues with understanding how to manage fixing an issue re: claims and how to move forward from here.

Some details about the two plans:

Job A: I’ve head this job longer, pretty barebones insurance plan with high deductible, however affordable for having my husband on as he doesn’t generally make use of it or go to the dr. I’ve recently upgraded this plan to a good one as I’m fairly certain I’m to be laid off in the coming months with Job B.

Job B: newer job of a few years. Employer pays 100% of employee premium, however this is not extended to spouses and is too expensive for us. That said, i am currently pregnant, so I plan to go to the doctor a lot in the next year. As a result, I have been using this insurance exclusively as the deductible is manageable and has much better coverage. I’ve never had a problem with claims before.

I recently went to the ER due to a complication in my pregnancy, however, and it seems that the hospital billed Job A first, who has since denied all claims and seemingly left me to pay the full bill due to my having two insurances (the EOB said I needed to provide a COB, which I wasn’t aware I was supposed to do to begin with). Job A insurance have been saying they need to run an investigation and that whoever I’ve had longer must be the primary. I have not been able to speak with anyone at either insurance co nor hospital due to the holiday breaks and don’t know if that rule is universally true or not.

Because I’ve never had a problem before when previous claim at other places were billed to Job B first, is this something that I simply can fix by insisting that the hospital bill Job B first, or is this much more complicated than that?

I have a new OB appointment tomorrow and don’t know what to tell them for how to bill my insurance as I don’t even know which is primary anymore and am so overwhelmed and lost. Please help.