From my ten year experience of going from 15-20 alters down to just 1 single alters, with some fragments here and there - I would say that it is not necessary to uncover every single alter and what they hold, for some of your alters are connected to each other, therefore they will leave or integrate when their counter part does.

Just as one does not have to healing every single little wound in their past in order to move from the trauma.

LoVe,
Rhapsody -