One of my therapists once told me.... DID type alters do not just suddenly appear one day, this kind of alters are there the persons whole lifetime. when I feel like new alters are showing up it can be one of two things in me....

1. they have been there all my life I just was not co conscious with them, to know they existed.

2 they were not one of my dissociative type alters but related to my other problems like medication induced, psychosis induced, physical health problems induced...

I have had both situations happen to me. the first kind was never triggering or upsetting to me because whether I knew it or not I had alters since before I was 5 so finding out another one was there was nothing new or triggering to me. but I did sometimes wonder why I was not co conscious with all my alters all at once instead of part of the integration/ healing process. in me it was ok because it showed great progress and healing and that one day I would no longer be DID.

my suggestion is talk with your treatment providers they will be able to answer your question as to why "new alters" keep coming up for you, and get you on the right treatment plans so that this does not keep happening for you.