short version here in the USA there are now two dissociative disorders where a person may have alternate personalities....DID and OSDD (other Specified Dissociative Disorder) OSDD has less than marked problems associated with things like loss of time (not knowing/not remembering what happens when the alters are in control.) where as a person with DID has more memory problems associated with when the alters are in control, personal information and such...

that said with both disorders there is something called co consciousness. thats the psychological term for knowing /hearing and sharing what the alters are saying, doing and knowing. some people have more and others have less and some people have no co consciousness. its all individualized according to how each persons system of alters are comprised, and what each of the alters jobs, purposes and reasons for being created are.

here where I live yes there is always a concrete central person, here that is called a host (person in which the alters reside/live with in. that said with some people with DID there has been so much trauma/abuse that the central person has been so traumatized that the host person is so buried in side that there are alters who's job, purpose,reason for being is to take turns being in control while the core/central/ host (which ever term applies) remains unreachable/ protected/hidden/ and in some cases unknown to the alters to where they dont know there is a core/central person..

think of it this way if there wasnt a central/core person there wouldnt be any alters because the alters had to come from somewhere. the alters are parts of a whole...kind of like you cant get orange slices from nothing. there has to be an orange in order to have orange slices, there has to be a physical person (core/central /host) in order to have alters. the alters are created when a child (core/host/central) has been through extreme abuse before the age of 5 (according to my locations documented statistics)

with DID reality testing remains intact meaning yes the alters know what they did when in control of the body example rainy knew she would cry when she was in control of the body, would know that she was talking with my wife or my therapist, would know her doll was in her arms, would know what she was saying after she had said something.

it was me the aware self that did not know what went on when rainy was in control due to my lack of co consciousness. Reality testing remains intact for the aware self too (I knew and still know whats real and what isnt and knew what I was saying and doing when I was not dissociated., wasnt hallucinating (was not seeing and hearing things that were not real....)...

other locations and treatment providers may explain DID and your questions in a different way.

if you feel you have DID or any other mental disorder you will need to contact a treatment provider who can diagnose that with in you and help you get into the treatment plan that is right for you.