I'm not sure specifically who 'Lorrie Walker' in 'Based on a True Story' is without more context. It could be a character in a book, movie, or other form of media that is inspired by real - life events.
The Snow Walker does have roots in real events. However, it's likely that certain details were modified or embellished to make it more engaging for the audience.
Well, Ghost Walker is purely fictional. It's the imagination of the author, not drawn from any true story. The plot and characters are all made up to entertain and engage the readers/viewers.