its just a definition change since 2013. nothing to worry about.

remember when you were working on fractions in math class. ..

when you cut an apple in half you dont have 2 whole apples (multiple apples). you have 2 halves of one apple.

when you cut 1 pie into 8 pieces you dont have 8 whole pies. (multiple pies)
you have 8 slices of pie and each slice equals 1/8th of the pie.

the new definition is like that where the American Psychiatric Association defines a person with DID does not have many/ multiple personalities. they have one personality that has been broken up into parts.

example

I had one personality (all my memories, emotions, senses, experiences, how I thought, talked, behaved all of it that was what and who I was)

then before I was 5 extremely traumatic things happened to me that I was unable to handle.

this made my one personality break up into different parts doing their own things.

each one of those parts of my personality was not another human being with their own brain and body, they were part of me living inside of me.

thats all it means when a treatment provider says a person doesnt have multiples they have parts of their one personality.

another way of putting it in new language by APA is the phrase "less than one"

according to the APA a person with DID doesnt have multiple personalities, they have one personality that was broken up into many parts, each part is a fraction of the whole just like the orange with the many parts inside it. or the pie that has been cut up into many parts of the one pie.

just updating definitions of the old ways.