I never had alters that wanted a mommy though during the time I was in foster care while social services and my parents were prosecuting my abusers , I did want to go home to my mother while in non dissociated state. this need to go home and be with my mother was one of my triggers to where I would dissociate into an alter who's job, purpose reason for being was to make sure all my basic and self nurturing needs were met...

example missing my mom would cause me to feel disconnected, numb, spaced out, then an alter I will call for this post Selina, would take over, find my favorite items that I had with me from my parents and climb into bed cuddling the stuffed dog, my mothers shirt, and a book that my parents gave me. Then Selina would put on my mothers shirt, climb into bed, pet the dog and read the book.

my point is that everyones internal system is comprised in such a way that ensures everyone is taken care of and able to survive those traumatic times. Since you know what your alter needs Im guessing you are co conscious with this alter. This means that you can ask inside to find out who has had this sense of agency of taking care of this alters needs that ensured your survival during the traumatic times. Maybe you can ask inside to find out what needs to be done so that you can do that for your internal system.

One thing about my system was that even when I did not have co consciousness doing things that comforted me also comforted those inside of me due to its all one physical body and a natural dissociation filter. A dissociation filter is my locations term for how the alters know when they are supposed to take control. they are connected through their co consciousness ability to know when the body they are in has dissociated (some people call it when the host/ alter that was in control is/ was triggered ...there are many different words for how alters know when the person they reside with in is not in a non dissociated frame of mind..)

my point is most people with DID already have some sort of "filtering" system where the alters just know what and when to do things. maybe you can ask inside for your alters help with helping this triggered alter feel safe and comfortable again