So it seems like another alter was using the hand to draw while you were still the 'main one' in charge of the body? Is that what you mean? Kinda like a split co-habitation?

We may or may not have had similar experiences with drawing... I very vaguely recall some 'automatic' type drawings that were done when I wasn't one of the front ones, but I don't now enough about that to expand further.

However, this seems a little similar to me so I will mention it... more recently we have had curious experiences with simultaneously videoing and typing as a way of communicating with those inside. I turn on the video, leave it running in the background and then type questions to whichever alter I am trying to communicate with. Sometimes that has resulted in curious switching back and forth, or even co-presence where in the video I am typing a question while another alter is 'out' and responding in body language or speech even while I am still typing. Sometimes there is a switch back to me when I am typing and then you can see the alter come out again to respond, and sometimes we are both there (me typing, them in body) at the same time. It is bizarre and fascinating to watch back on the videos and time match the typed text to the responses.
So I guess that is kinda similar in some way???