Hiya, I've submitted all the evidence that I've submitted for the first round (and the residency) + updated the timelines (I briefly mentioned what we were up to every month). I've submitted new letters from the same people and the landlord who lived with us. We didn't have many letters addressed to both of us (just bank and insurance) but I've submitted letters we've received since the last visa issue addressed to us individually since it still proves that we live at the same address. We've also done quite a few domestic and international trips over the year so I've collected the boarding passes, printed out tickets, hotel bookings & our ''fresh'' photos. Got the new visa within two weeks, no questions or contact made.
Definitely no need to stress - INZ has already ''accepted'' your relationship so you just need some extra proof that it's still going. It's definetely mich easier than the first time around and people rarely have any issues with this.