The Kardashians are not backing down from their trademark dispute with Blac Chyna.

Kourtney and Khloe Kardashian and their sister Kim Kardashian West have reportedly tried to block Chyna's request to trademark Angela Renée Kardashian when she marries their brother Rob Kardashian and although their mother Kris Jenner has attempted to dispel tensions, the siblings will not withdraw their opposition.

A source told TMZ: ''It's nothing personal against Chyna, just business. They feel adding an extra woman to the roster will dilute the brand they've worked so hard to build.''

And the siblings are also apparently suspicious that Chyna never tried to trademark her name when she was with her ex Tyga, who is now dating their sister Kylie Jenner.

While the trio enjoy a cordial personal relationship with Chyna, who recently gave birth to her and Rob's daughter Dream, attempts to negotiate have been unsuccessful because the model's lawyers have reportedly gone ''radio silent''.

A source close to the family previously claimed the girls' lawyers ''automatically oppose'' anyone who places a trademark request for their name.

The insider claimed: ''Their trademark attorneys automatically oppose anyone trying to trademark 'Kardashian'. I doubt the girls were even aware. Everyone loves each other. It's just business.''

The news comes after Chyna - who also has four-year-old son King Cairo with ex-partner Tyga - was reportedly left ''heartbroken'' by the feud.

A source said: ''Chyna is really heartbroken over this whole name feud.

''She thinks it's just sad that the Kardashian family can't stop thinking for themselves and just accept her as one of them. Her and Rob [Kardashian] are practically married and she's the mother of his child - why can't they accept that?

''She thinks they are total fakes, pretending to welcome her into the family. It was all bulls**t.''