User blog comment:TheToughGuy/Transferred To Bullworth (TheToughGuy): Chapter 1/@comment-2173402-20160325035833/@comment-2099017-20160325140600

Kate is Roman and Mallorie's daughter and Greg's cousin. If you've done the revenge ending in GTA IV and played a while after the credits, Niko receives a call from Roman telling him that he's sorry about Kate's death during the wedding and that if it's a girl then he and Mallorie would name her Kate. It is believed that the revenge ending is canon since in GTA V, Niko has a Life-Invader page and has Roman as a friend on there. You can see it on Jimmy's laptop on the kitchen table when he claims to be "filling out some resumes for some jobs".