Rob Kardashian's family are reportedly not thrilled by the news he is engaged to his girlfriend of three months Blac Chyna. Rob Kardashian's family are not ''jumping up and down'' at the news of his engagement. The 'Keeping Up With The Kardashians' star announced he is set to walk down the aisle with his girlfriend of three months Blac Chyna but the Kardashian and Jenner clan are reportedly less than thrilled.A source said: ''No one [in his family] is jumping up and down with excitement today. They have made a united decision as a family to not comment on social media yet about Rob's engagement. The news is not shocking, and not totally unexpected. ''There has been a fear that Blac Chyna is manipulating the situation with Rob.That he is getting himself into a situation that is not ideal for him. Blac Chyna has been great as kind of a rebound. As someone that got Rob out of a dark place, that helped him get motivated and healthy again. Let's just be honest, no one is really hoping for a marriage to happen.'' Meanwhile, the happy couple are said to be thinking of using their upcoming wedding as a way to attract viewers to a spin-off reality show about their lives. Another insider added to PEOPLE magazine: ''Rob and Chyna have been thinking of ideas to make an amazing spinoff.An engagement and wedding planning are of course very interesting and would attract viewers. ''The engagement seems so sudden. It's hard to take it 100 percent seriously when you know they have been thinking of business ideas to make money.''..