Do I need to create a 529 in Vanguard to transfer to Fidelity?

Sorry for the confusing title. Here is my situation.

My stepfather has 529 accounts for both of my children at Vanguard. He has dementia, and my stepsister is acting as his POA. Due to his condition, she is closing his accounts and transferring the money to us.

She is telling me that I need to set up 529 accounts at Vanguard first, so she can transfer ownership, and then I can do a rollover request to Fidelity.

Is this accurate? It feels like a needless step.