BPS & BPA treatment with 80% Ethanol
I agree with M. Farooq, a test that might work is cutting small pieces of thermal paper and placing them in a tube with grain alcohol or a facsimile, and allowing them to soak for a few hours, then send the sample to a lab and ask them to test for bisphenol A/S. If you can, it's just better to ask the company.
Edit: you can just soak them in grain alcohol. It's hard to do a specific test for bisphenols, but I found one for phenols in general.
Procedure:

Prepare a dilute solution of ferric chloride in grain alcohol.
Using an eyedropper, add a few drops of the solution to a teaspoon of your solution to test.
If a color change is observed, phenols are present.

This is not ideal, but it's the best you can do.