I went to Glencoe as a teenager, and both the landscape and the subject matter are pretty bleak, but I have no idea about any sources. Have you checked Wikipedia's list of sources for the massacre?
The first I ever heard of this was in an Irish Rovers song, when they filmed some episodes in Scotland. The song starts around 3:30 in:
Lately I've been booting around a Highlander/Merlin crossover idea, with some of the historical flashback material based on music I've heard over the years. Glencoe isn't one of the historical events ever done on the original Highlander TV show (that I recall), so I wouldn't be stepping on that show in that respect. But when plotlines and dialogue suddenly start coming and next thing I've got 3 looseleaf pages of notes, it's something that's pushing to be written.
While
Merlin played fast and loose with history,
Highlander made more of an effort to get the historical era flashbacks reasonably accurate (allowing for the inclusion of Duncan Macleod or another of his Immortal friends/acquaintances being there and part of the event).
Yes, it's an extremely grim historical event. But there are a lot of things I write about that are grim. This idea won't leave me alone, so I'd like to try it. I tossed RL history out the window for my King's Heir project. I'm not doing that with this project. That means research.
Since I really don't know much beyond what the song says, plus a podcast I found (and slept partway through since podcasts put me to sleep; I really need printed words to read to learn stuff), this is going to require explaining it to someone who really doesn't know much at all of this period of history.
I've read the Wikipedia article, and it's a
lot of information. It's going to take time to digest it before deciding which links to follow.
(speaking of reading stuff that's grim... if I could make it through a book about the Spanish Inquisition and do research on various torture/execution methods in ancient Rome and in medieval times, this is probably not that much worse, except that children were involved)