The problem with the canon (meaning the OS) is that, over the years, it became somewhat convoluted leaving lots of logical gaps. I also noticed that Ms. Parker took some liberties with it in Angelique's Descent (a novel which I loved, by the way), but to make her own work flow she had to move this, turn that, twist that thing over there, even when having to reconstruct direct scenes from the series.
When I wrote my DS novels in the late '90's (hoping for them to be published in the quickly risen and then fallen Harper-Collins series), I had to do the same thing. For example, I had to jettison the whole thing about the members of Collinwood remembering Quentin's haunting because - since it ended up never happening - there would be nothing to remember. Some, like an elderly Roger (and that novel was set in 2000), had vague, inexplicable memories that remained, despite the paradox.
Gerard