@babbsjoy Congratulations on being proactive in managing your care, insurance changes often carry unhappy surprises.

First, if at all possible, get a refill of your Tymlos prescription to tide you over while negotiating with the new company! We had this issue last year and nearly ran out of one crucial medication.

Second, do not assume that because the new company uses the same pharmacy that they use the same formulary & the same rules.

Your next steps are-
Get a copy of the new insurance plan Drug Formulary (list of covered drugs) and the list of codes that indicate what actions are required before the will fill your prescription - prior approval, what the standards are for approval, etc.
Determine if the specialty pharmacy fills orders for this drug under the new plan (we found out that it is not always the case), otherwise you may need to find a new supplier.
Finally, get a copy of the appeals process for any denials in writing - with the contracted timelines for response.

We have been under a new pharmacy plan this year with my long-time insurer. The new plan not only used the same pharmacies, it had exactly the same Pharmacy Benefit Manager.
Yet they not only required new Prior Approvals for medications we were already using, but also denied those approvals and I had to appeal.
To add insult to injury, they stopped supplying said medications through their Mail Order, but failed to notify us that they did it, filling was delayed by weeks as we had to find a local supplier and pay a higher price.
Just when I thought I had seen everything, the real surprise came yesterday, when they refused a medication I have used for over 10 years, and said I had to go back and repeat the "step therapy" to prove I need it - and it is a generic drug!

I hope you have smoother sailing!