Chelsea is fair game now because she has inserted herself into the public domain with her tales of 9/11.
The Bush girls should be left alone at the request of the President unless they truly do something newsworthy. Like getting busted again for underage drinking since it will result in 1 of them going to jail. If the law is upheld that is.
Chelsea should be left alone as well, unless she starts telling more tales of 9/11 that dont match up to the 3 different versions already told.
None of them are elected to anything and none of them hold positions of power or public trust.