When I signed up for Medicare in 2010, there was no mention whatever of a secondary provider. My primary did become my secondary,but by my choice. I could have just as easily dropped it.
I remember now why it wasn’t possible to drop my secondary provider, formerly my primary. That provider is still my wife’s and two minor children’s primary provider and it’s a family plan.
Also, my secondary provider, which is my former employer, pays my medicare premiums, when my wife becomes eligible, they will also pay hers.
They don’t actually pay the monthly premiums but send me a check every 6 months to repay me for paying the premiums.