Well perhaps when making a family tree for this you might want to go backwards, and keep it simple.
Perhaps you should start with the "youngest" at the bottom/top and then put his/her parents. then the parents parents, and so on and so forth. don't even worry about aunts and uncles at first.
Here's what I'm thinking of.
Youngest
Parent Parent
Grand Parents Grand Parents (GP)
Great GP Great GP
Then once you have that down you can branch off from there starting at wither the mother or father's side.
I don't know if it makes since to you but it kinda does to me. >.< I've never done an immortal family tree before though.