Why doesn't Kate and her brother use "Russell" for their surnames?
Considering that they consider Kurt Russell to be more of a father than their own biological father.
http://www.lipstickalley.com/showthread.php/891541-Bill-Hudson-Slams-Goldie-Hawn-Disowns-Children-Oliver-Kate-Hudson-quot-I-Would-Ask-Them-to-Stop-Using-the-Hudson-Name-quot