How does tricare as secondary insurance work?

Hi!

I’m a military spouse, covered under tricare, considering enrolling in my employer’s medical insurance plan too.

Why? Because I don’t like going on base (~45 minute drive each way + very limited appointment availability) and find their referral process frustrating.

My employer offers a platinum HMO plan that is 100% employer paid. I can have a PCP right down the road.

But I am currently in online therapy and while my therapist accepts tricare, they don’t accept the new carrier. The new plan would also have a $30/visit copay. Would tricare still cover my therapy? It’s currently $0 out of pocket for me.

So my main question is if a provider needs to be in network with BOTH insurance plans to get the dually insured benefit.

Thanks!