To me the evidence that seems solid suggests the following:
They secure the tent and go down to the tree line. The "two Yuris" may have gone down first, but they die first, by the fire. At this point it's unclear what the sequence is, but it also doesn't appear to be the key point, which to me is why three headed back to the tent. I think a good possibility is that Zina and Slobodin were with the two Yuris, whereas the other 5 were digging out the den (it's possible some of the 5 warmed up first and then went to the den area). After one or both Yuris die, Zina loses faith in Dyatlov's leadership/decision-making (as we read about in the diaries) and decides to go back to the tent. Slobodin follows her (to try and get her to go to the den) or goes with her, but falls and is knocked unconscious. Dyatlov gets back to the fire area (perhaps puts on a vest worn by one of the Yuris) then goes after Zina to try and convince her to go to the den. The reason this makes the most sense is that there is no evidence that the "returning three" were cooperating or helping each other, and the den idea would seem to be much better than going back to the tent at that point in time (almost certainly before sunrise). Because we don't know when the "den 4" fell into the depression and onto the rocky creek, we can't say if those 4 held out longer than the returning 3, at least in terms of my understanding. However, it would seem that at least the last 7 deaths (or laspses into unconsciousness) all happened within an hour or so, and doesn't affect the explanation as to what likely happened.