It's not imperative for the first four, which were deliberately published out of chronological sequence and were meant to be standalones only loosely connected by a theme. So those four can be read in any order, as long as they're before the other four. Indeed, I don't think Seize the Fire has any impact on anything else in the series, and The Struggle Within, alas, has very little impact (basically just solidifying who the members of the Khitomer Accords are). Indeed, one could make a case for postponing Rough Beasts until just before Plagues of Night and Raise the Dawn, because those three essentially form a trilogy. Not to mention that PoN overlaps the events of the preceding four books chronologically, beginning at the same time as Zero Sum Game, so one can't really do a strictly chronological reading without going back and forth between books.
The Typhon Pact is also an important part of the background of the main story of DTI: Watching the Clock, which takes place from March 2381 to February 2382. Paths of Disharmony is also loosely followed up in TTN: Fallen Gods, which takes place right after the former in November 2382. Additionally, Sela's adventure in early 2383 in TNG: Indistinguishable From Magic is referenced in the middle of Plagues of Night.
Well, I'd call it a secondary element there. The Pact is present in the narrative, but far from central to it. The Pact plays a much larger role in the first two volumes of the Cold Equations trilogy, especially the second.
The specific events of the Destiny trilogy don't directly impact the Typhon Pact books, but to get a clear understanding of the state of the universe during the TP series it would be helpful to read Destiny.
Literary Treks has finally been covering this series and we reached Paths of Disharmony by Dayton Ward!
Believe or not, I am still struggling with this. It sat on my writing desk for years, with a bookmark still only about one-sixth into it. It was such a hard slog. I can't explain why. It was just sloooooow. Unexpectedly, I was asked to Beta-read a draft of Dayton Ward's "Paths of Disharmony" (due to its Andorian-heavy storyline) and my father was pronounced terminally ill while I was doing that, so I found it very hard to go back to "Seize the Fire". Instead, I jumped forward to more fascinating arrivals: "Full Circle", "The Light Fantastic", the "Seekers" and "Cold Equations" mini-series, later "Titan" novels and, more recently, the "Discovery" and "Picard" novels. A few weeks ago, I put "Seize the Fire" back into my travelling satchel and - when I can stay off my iPhone - finally made some progress. I recently reached the encounter between the Gorn refugee and the Titan's Gnalish crew member (previously retro-identified as the same race as Sord from Filmation's TAS). Suddenly, I am actually enjoying the book! Maybe I will finally get to the rest of "The Typhon Pact" and "The Fall". I hate seeing them lined up on my shelves, neglected and unread. TNG: Paths of Disharmony cover slick by Ian McLean, on Flickr I can only speak of "Paths of Disharmony", but I am biased. I was in Blue Heaven. I even bought it in German! And I don't speak German: Dayton Ward's Star Trek: Typhon Pact: Zwietracht by Ian McLean, on Flickr It contains a bonus essay by Christian Humberg in the back of the book - in German, of course - seemingly discussing the Andorians and Aenar of "Enterprise", the DS9 Relaunch novels, "Andor: Paradigm".