As I understand, one condition has to be met, by dead people, in order to not disappear: to have at least one alive person that remembers you.
There is one person that disappears due to being forgotten, and then Hector explains Miguel that there must be at least one alive person that remembers you (and insinuating that Miguel does not count, right now, as an ALIVE person).
When Hector was about to being forgotten by Coco, they gave Miguel their blessing without conditions, and Miguel was back alive, and hurried to meet Coco and tell everything with the hope that she does not forget her father.
My question is did he actually need to hurry? after all, he was back alive, and he remembers Hector. Wasn't enough to be (Miguel) alive and remembering him (Hector)?.
On the other hand, I was explained that people who knew you while being alive, must remember you in order to not disappear (and so, it was useless whether Miguel could remember Hector). If that scenario is the right one, and only counts whether Coco remembered him (since Imelda was dead, and is not stated whether another person knew Hector besides Imelda and Coco) then... Why didn't Hector Disappear when Coco finally died?
Otherwise... What am I missing here?