i like the fluid idea TR, that's how we are working with trying to find out about our system right now. But we use objects instead... we have a few crystals, a couple of meaningful small objects and stones etc. We can manipulate them to show relationships between parts etc. Who spilt from who, which events or things they deal with and stuff like that.

In the past (I am talking 90s) we initially wrote lists of alters as we came to know them. As we got to know more we made a timeline kind of thing, and put on what info we knew, and added more as we learned more. Like we would map on the timeline what we knew about when an alter first appeared, when they were most active, when they stopped needing to be out so much and things like that.