I act childlike in therapy when I talk about feelings for my T or when we talk about the child part. When I want her to hold my hand, it used to be the child who wanted that, but now I think I may be more mature and I just like to be touched, period.

I say "it's not fair" in RL, or I used to a lot, as an adult. That's certainly childlike!

I have BPD and don't do DBT either. We do IFS and EMDR, and lots of other things like meditation, walking and talking, and art therapy.

I think regression in therapy, as ECHOES said, lets me be less inhibited and tell my T what I'm feeling. She helps me because she specifically wants me to feel that the "child" part is there so I can tell my T how "she" feels and what she needs from me and from my T.