https://en.wikipedia.org/wiki/Recovered-memory_therapy (see research section)
Some of the techniques included hypnosis or even giving the patients (including children) sedative-hypnotic drugs before pressuring them with the leading questions.
If they could eventually get the person or child to claim to have some memory of the event (after asking a lot of leading questions and maybe even drugging them) they considered it to be a recovery of the memory.
On top of that, I have legitimate memories that were not traumatic, but still related to the same traumas because said person attempted to encourage these activities throughout my young life on rare occasions. I didn't remember what happened as a kid, but I knew something wasn't right and I wasn't comfortable. It wasn't until I was almost 30 that I had my first "flashback" which was a fractured memory, I still remember it looked like a faded photograph in my mind, and it was accompanied by an extremely uncomfortable feeling.
The re-surfacing memories aren't real in a sense, but in my case they aren't entirely fake either.
I wonder if it's possible that things can be completely imagined with absolutely no basis what-so-ever in certain circumstances, and I also wonder how difficult it is to discern that. It seems to be a difficult concept to manage.