welcome mike...I know its confusing to you why you know of the others but they may not know of you..you being able to know/share knowledge of the others but they not you is called co consciousness. everyone (the host person you live with in/share a body with, you and the other alters) each have your own amount of co consciousness Co consciousness is having the ability to know the alters are there, having the ability to hear each other, having the ability to communicate with each other.

feeling like there are more alters in the same internal system is ok, sometimes that belief turns out right and other times it turns out wrong. dont worry about it,if there are more alters then the host person knows or mentions, thats ok, it just means that level of co consciousnes between those unknown alters and the host/other alters have not been developed yet.

example when I was a child an alter named wolf was created. Wolf and I did not get to know each other until shortly before I and my alters integrated. I had no idea she existed. She was older than I was (4yrs old) when she came into being (70yrs old in animal yrs, 10 in human years) because one weekend I was lost in the woods with an abuser. I now know I needed wolf in order to survive by using the wolfs cunning/smarts/wild ways in order to survive the abuse and being lost. I never knew she was there, just one day she came out to talk with my therapist about that traumatic event. I never developed co consciousness with Wolf never knew she was there until my therapist was surprised by a visit from her, but healing was still possible, and Wolf integrated/became one with me just like the other known about alters.