some internal system of alters are set up so that they have some alters that do what is called here "evolving" rather than "categorical" (the DSM uses the term distinct) alters. Alters that are able to evolve are able to learn how to do things like self nurturing, self calming therapeutic exercises like what your therapist was trying to teach you and your alters. many people think every one of their alters have only one way to be, because up until they learn a new way they do present their selves as having only one way to be...

example until you were taught to do a higher level of math all you could do was simple addition, and you had one way that worked for how you did that simple addition. but after you were taught a new way you evolved to where you were able to do subtraction, multiplication, division...

some alters can evolve going from being a categorical alter to being an evolving alter. the only way you know whether your alter is strictly categorical and cant evolve is if you try what your therapist wants you to do.

my suggestion ...maybe you can let go a bit and entertain the idea that maybe this categorical alter may actually want to change to an evolving one.. give your therapist a chance and try what shes trying to teach you and your internal system. you may be pleasantly surprised. besides DID type alters have their own ways of being so what may end up happening if you remain closed on this idea is your alter taking control and doing what the therapist wants regardless of how you think they present their self.

thats what happened to me many times, when ever I told my therapist I cant do this or that and my alters dont do this or that, my alters took control and did what ever I didnt think they should do. alters truely have their own way of being and their own way of perceiving / thinking and behaving. that means if they want to evolve or change then they are going to evolve or change despite what we want or think of them. If I didnt want to go out drinking an alter did it any way, if I didnt think an alter could / should cook they tried to any way...