That T has no freaking idea what she is doing! And she calls herself a "specialist" in DID? She has seen you three times and doesn't even know IF you have a system let alone KNOW the system.
Aside from the whole question of IF you have DID, which she cannot honestly or professionally determine after giving you a "test" for it some number of years ago, and now seeing you a grand total of three times more recently. Aside from that incredibly dodgy practise, if she believes you have child alters caused by trauma then she should darned well know that they were created to PROTECT you, and she should have no darned business messing with that protection system until both of you have more knowledge about what and how and why they are there. She has no IDEA what they could be protecting you against, and what outcome there would be from prematurely messing with them.

OMG I hope you run away from her and do not ever return to her. That is NOT how safe, professional, and researched therapy for a trauma based dissociative disorder should go.

I was diagnosed with DID about two years ago and since then my T has followed the international guidelines for the treatment of DID, which have us still firmly planted in stage 1 of treatment which is ONLY about developing a connection with the therapist, developing grounding skills and the ability to stay in the present, and very slowly developing our knowledge of the system. At no time has my therapist wanted to "rearrange my system".

You don't know this woman, she doesn't really know you, and after seeing you for three hours she wants to dive in and rearrange your whole personality system? Do you really think that is a good idea???? What the heck does she know about you?? NOTHING.

Please protect yourself from this woman. Look, I know we shouldn't really tell other people what to do in their own therapy when supposedly their own treatment provider knows them and the situation best, but please, this is one very glaringly obvious case where - if you are telling us the truth about all that is going on - this woman is absolutely not doing the right thing for you, a client she barely knows. Even if she DID know you quite well back then, which I don't believe she did from all you have said, now is not then and she should not be acting on prior knowledge.

Please stay safe.