If you have insurance I’m not sure what the warranty even covers! Again I wouldn’t worry about it. If you find a local jeweler with a good reputation and an in house bench they can likely order you a mounting from Stuller for very reasonable cost. Their website has 1000s of designs.
And @haleyn17 - lab or not, I think something so special and beautiful is worth the re-set, and I'd be trying to retain as many of the original elements (ie the melee and the metal) as possible.
Re moving the thread, since the title is "Advice needed - 3.52 carat", the focus is kinda on the center stone and how to maximize its presentation and beauty. There's no problem with this - threads get moved all the time.
I'll be really interested to see where you end up with this; all the possibilities are gorgeous!
@haleyn17 If you unsoldered everything, would you be left with the e-ring, the insert, and two anniversary bands? If so, could you (1) get the jeweler to fix the NSEW orientation for the e-ring since the insert’s cathedral setting won’t be an issue anymore — or maybe even get a six prong if you are worried about security — and (2) wear the e-ring with the two anniversary bands either stacked on top of each other or sandwiching the e-ring? Sounds like the insert is really the big limiting factor here. You might just have to be okay with reusing the metal and stones for something else, but seems like this may be the easiest solution.