I think that docuenting who is a gardian or legal parent is just as important as documenting who the bio. parents are. The difference is documenting the gardianship/adoption is an event and not part of the family line. This will aid anyone to fully understand all events that transpired to get to that point and when. Also the partner will be listed as a spouse and within that person list the event of adoption/gardianship. And the child can be tied back to the bio parents through the correct line. If you don't document the adoption/gardianship you will lose perspective of that history of events that occured.