It took a long time for us to come to that understanding and accept that we are one person... we are still walled off from some parts, so I guess some are not there yet, too. But when we first began to gain awareness of each other some had an adamant denial of any relationship whatsoever.
Dissociation works. It does a good job!

Your T is right. It takes a long time. And it really can't be rushed. You may seem to make progress at times and then something might happen and the dissociative walls might go up again. Our front group is the most cohesive it has ever been, and it is because it is managed by me, who understands that we are all part of one person and that we need to come together. I have no denial. It is easier for me because I am less emotional. The more emotional ones struggle with accepting stuff because they feel it more. It is much harder for them.
I am waffling. Sorry. But yeah, it takes time (because it needs to!)