unfortunately there may be nothing you can do. each persons system is set up to ensure the wholes survival and protection already through what each alters sense of agency they have. it may be for some reason you dont know yet this alters sense of agency is to be negative, as in letting others know she thinks what she says and does it bad and feeling unwanted.

maybe what will help you with your system is what helped me.... to learn the basics of how your brain dissociates, and how and why your alters were created. maybe this will answer why this alters sense of agency is what it is....

example one of my alters sense of agency was the emotions of worthlessness, bad, and other not so nice / negative stuff. while working with my treatment providers I discovered the reason that alters sense of agency was what it was, was because during an extremely traumatic abuse my abusers constantly told me these things. because I was in a dissociative state of mind these statements and attitudes of my abusers were stored in my unconscious memories and as such became an alter with this negative sense of agency.

after I understood how my brain dissociated and caused the creation of my alters it was easier for me to understand my alters could not be forced to change who and what they were.... it was just their sense of agency and all I could control was me and whether I used what I was being taught in therapy to help me to not dissociate.

my suggestion is if this continues to bother you contact your treatment provider, they will be able to help you to learn what you need to in order to understand your system and do what you need to do so that this alter will no longer be causing you problems.