your SOS sorry but only your own treatment providers can help you to discover why your alters personalities are now breaking down, losing cohesion with their sense of agency....

with in me when this happened it was the final integration process of all my alters letting go of their individuality and becoming one whole person again with me (in other words the healing process that makes it so that a person no longer has DID.)

my suggestion is contact your treatment providers. they will be able to help you prepare and understand this part of the healing process of no longer being DID or OSDD.

that said in my location this term disintegration is used in another way for other mental disorders for example with borderline, and other mood and behavior disorders it means a person is having problems with things like depression, anxiety, and their functioning levels of self care\hygiene \ trouble maintaining their daily life.

the fix for this is medication and sometimes if the depression is the cause ECT (shock therapy) or inpatient treatment.

if this is what you meant again contact your treatment providers they will be able to assess why this is happening to you and adjust your meds, get you set up for more intensive inpatient treatment options.