Molly?  In White Night, with one of the early victims of the Whampires.  Harry took her to the morgue, and Waldo let her do her Sensitive thing.  It let Harry confirm there was a serial-killer.

oh 🤦‍♂️ my mind went to the wild wild West movie and it's literal version.. I couldn't place that scene anywhere in the DF tho lol

The other thing is, Faeries are tricksy AF.  They glamour stuff more-readily than Harry uses fire and force.

Molly could have opened a Way, and hidden that behind a glamour.

that's just straight up limiting what a way is and how it works quite frankly.
Harry literally monologues on him making this mistake on his own understanding of how complex making waypaths is to drive home the point. A way is not simply a tear in the air.
Remember they're making the way to get through the veil, the sheer lining between reality. A veil is something that you can usually step right through..
Case in point Mab, Maeve, ect appearing with very little disturbance besides extra cold. Either from Maeve being lazy or Mab simply existing.
What we're seeing is just the flavor of the way maker.

They wanted the Word of Kemmler; I don't know why they thought there were any clues there.

summon up Mr Bartleby and ask him questions maybe? Or the ghoul just needed fed..

So, the meta experience on this is vampire courts equivalent of seven sins. I fathom each court was brought in by their originator as a causality of choice in one of the 7(it's been theorized which would be which in the past here, can't remember all of them) mainly born from Jim picking an arbitrary number like 7 specifically for the courts but then only fleshing out the 3-4 major ones he had actual plans for.
So, sorta like demons they technically have a place in reality, though they have real bodies they are not actually welcome here. Bad housemates, Dresden evicted some for us lol.

It's winters cottage, summer hangs around cause of balance.
*Per woj btw, it's MW's cottage..

  Except if you look at Harry's style, he still uses rings, bracelets, firing rods etc..  It was even truer when he was younger, Justin would know that.

what does that have to do with Justin, who can call fire to his arm and not burn himself 🤔
And had Elaine to help, who I don't recall needing any focus for the exact same spell in SK.

Re: The larger sense of source material, I think Le Morte D'Arthur by Thomas Mallory may be a good candidate for sourcing and influencing Jim's interpretation.  I also think that it would be interesting if Elaine Mallory had some relation to the Arthurian legends.  I haven't read Le Morte in years, but may pick it up over the holiday to see if anything jumps out.

Mort and Mallory both stick out to me there. mmm, wonder if we'll meet a Darthur lol?

I'm not sure, but I suspect Jim is too savvy a writer to hinge the entire rest of the series (from Mirror Mirror onwards) on a bunch of multiversal twists&turns, on 7 Harrys (Harries?) and alt!Kemmlers, etc etc etc ad infinitum.

I think most of his readership would find it not worth following the complexities.

He's already -- IMO -- on the borderline of "too complex" with 1 multiverse novel + 1 time-travel/retcon/repair-the-Sacred-Timeline novel.

🙄 he already did technically, Demon Reach.
Tho as is usual your misconstruing a simple concept and plot twist that doesn't "govern the rest of the series", that's the greatest thing about the DF, you can enjoy it on many levels. Plus he has the time travel book last? Heh, I disagree. What I said was a tin foil theory to begin with, I literally started with an apologetic don't try because it's nonsensical. To share your doubt immediately after our ahem, history is bad taste. Opinion vs opinion that's enough said for me..
However be aware "I'm not sure" is synonymous with "I don't think". And  when people try to simply unname a theory as viable based on that.. well, the saying goes,",those who say you can't shouldn't interrupt those who already are".
And this has been a point of contention on how people come at each other from it has been the gathering of much heated debate and mod warnings for years.  Because it is not discussion, it does not promote discussion. And it should not exist here. It drives people away as is it's intention and is a perversion of etiquette, designed as such. Quite frankly, I'll go all ten rounds with anyone who disagrees and all day after. Stop trying to bully me, please and thank you 🙏
(Oh and you have no idea what the original theory was, because seven of nobody is running around when bodies are being tossed behind them to escape.. and proper etiquette would be to do as I asked previously and be curious about that)