One approach is to get a notebook and write back and forth. Write what you want to say to them and ask them to write back. It has worked with us when we have an insider who won't talk.
I started by talking in the privacy of my own safe place. They hear you. Whether they choose to answer is another thing.
Its a process. It takes time.
Have you done any reading on DID? Ther are some good books that talk about how to open communication and create safety inside.
white iris