Taking over as Power of Attorney

My father has MCI. Early in his diagnosis, we met with his Fidelity advisor and my dad indicated that he wanted me to manage their account. My mom is still good but is uncomfortable with finances. I am a CPA so they were comfortable with me handling things.
Fidelity has their own documents so I worked with them to submit the DPOA and complete their paperwork. Once that was set up, I have had no issues with managing my parent's accounts.
I'm less certain about the bank accounts. Again, some time back my parents added me to their bank account and safe deposit. So I can transact business their as well.

Thank you so much for that. I am feeling very comfortable with the relationship I have with our advisor at Fidelity. We talked about the durable power DPOA vs simple POA as someone else had mentioned. I am the DPOA and all is good. I did have to sign papers at Fidelity with a notary.
We have not involved our adult children other than to tell them where the big red estate planning book is and who are key people are - Estate Atty, CPA, and Financial Advisor. They are grateful that I have taken over and trust that I am making good decisions for my husband and I. Luckily our children are all self-sufficient and just want to make sure I have handled things enough to consider our needs to enjoy each other and travel while we can and have considered long term care for the future. That is what I have been working on.
Mind you, I was the woman who let her husband do all the portfolio and money management. I had no idea how it all was put together and what stocks etc we owned. Now I am learning all of it and more and reading everything I can about financial management. I have met with our advisor at least six times since March. It's been a journey but I am feeling more at peace, however becoming POA so soon was an eye opener.
Thank you and others for all your comments and I hope mine have been helpful here.

Like you I am a little confused regarding the POA and durable POA. Hubby and I have had all the legal papers for each of us in place for years; however, recently because of his Dementia diagnosis we were told, and I read it in the book “The 36 Hour Day,” that “A general power of attorney becomes void if the person who granted it becomes mentally incapacitated. A durable power of attorney authorizes someone to act on behalf of a person after they become incapacitated and unable to make their own decisions.” As a result we have gone back to a lawyer and had both of ours updated to durable with me having authorization over hubby and my oldest son having it over me if needed down the road. We are about three years in on this journey…it’s been hard making all the daily life adjustments, but we are making it…one day at a time.
I admire you for making the road trip. We have enjoyed traveling and I am not ready to quit. I have considered doing the same just the two of us.

I did it year's ago. I knew the day would come that if I was still living or our children would need all of the abilities to do what needs to be done. I made it about me..but it was about us both.