Marriage Won't Help Blac Chyna Trademark Kardashian Name

Kim, Khloe and Kourtney Kardashian are sticking to their guns when it comes to stopping Blac Chyna from the family name -- and neither marriage nor their mom will change that.

Sources close to the sisters tell us they will not withdraw their opposition to Chyna's application to trademark "Angela Renee Kardashian" -- despite Chyna's side saying there's no legal war brewing.

As we told you, BC sources say Kris Jenner reached out and promised to call off the lawyers. But our K sis sources say that's not how they feel about it. We're told it's nothing personal against BC, just biz -- they feel adding an extra woman to the roster will dilute the brand they've worked so hard to build.

We're told they think it's odd Chyna didn't move for a trademark when she was with Tyga -- although that's kinda apples and oranges. $1 if you know his last name.

Our sources close to Kris say the conversation those close to Chyna alleged the two had to smooth things over never even took place.

On a personal level, we're told everyone in the fam is getting along well with Chyna since the birth of Dream. Still, business is business and our sources say the sisters' lawyers have made several attempts to negotiate ... but Chyna's team's gone radio silent.