RMB, BC/BS is just a loose affiliation of like 40 different insurance providers. So each network/provider has its own PBM agreements.
My Anthem BC/BS plan uses one PBM (I think they use Carelon Rx), while CareFirst, Premera, etc. each have their own PBM agreements. So every BC/BS member may or may not include Vascepa in their formulary.
It's usually best to just ignore the "BC/BS" terminology.
RMB, I've never used the amarin coupon, if my insurance charges more than GoodRX I don't go through my insurance. I'll use GoodRX. IIRC someone here has used the company coupon in the past. Maybe North?