Fake descendants 
Having the last name of Jilani does not make someone a descendant of the Shaikh.  It just signifies that someone's ancestor has come from Jilan, or someone was a descendant of someone named Jilani.  Maybe someone became a Muslim on the hand of Jilani.  There are lots of Jilanies who are Shias and dead against the Shaikh.  After the 1947 partition, many people changed their family name during the crossing.  Even someone is a descendant of Shaikh, he can be a convert to Wahhabism.  I have seen some Jilani converts to Christianity.