this might fit: Confabulation. "In psychiatry, confabulation (verb: confabulate) is a memory disturbance, defined as the production of fabricated, distorted or misinterpreted memories about oneself or the world, without the conscious intention to deceive."

https://en.wikipedia.org/wiki/Confabulation

Anyone who has spent time with dementia or Alzheimer's patients knows how they
blend time periods, associations, even people into one another. Events from the
1940s become mixed with and added to events in the 1960s. You can't change
their minds, it's very upsetting to them. So you play along.