Margaret, I'm not sure if I'm following this correctly, but just want to point out that if you attempt to associate two people as siblings, and there is no parent identified, the system will automatically create a new "Unnamed Father" profile for the two siblings. I'm told that this is done because the data base doesn't keep track of sibling relationships directly, and only makes those associations through the parents.
If this doesn't apply in your case, just ignore the above, but it might help if you could provide a little more detail about exactly what you're doing, or perhaps an example.