I finally gave up on trying to figure out what my sister is up to in regard to mom. She texted me today that she is primary medical POA and I'm secondary. She also texted that I can handle her medical bills, nevermind I have no access to her money to pay them. I have nothing proving I'm on the POA and my limited understanding is that secondary can only take over if the primary cannot do her job. I told her as much and she claims that "under the concept of apparent authority you can act." I don't trust that, but I will call mom's insurance tomorrow and inquire. I assume they need more than just a phone call....?