The Kardashian sisters reportedly want to stop Blac Chyna from using their famous last name.
Blac Chyna, born Angela Renee White, is engaged to and shares a daughter with the siblings' brother, Rob Kardashian.
Kourtney, Kim and Khloe's companies claim that Blac Chyna's trademark would cause them to "suffer damage including irreparable reputation and goodwill."
They also say the model is "deliberately seeking to profit from the goodwill and popularity" of the Kardashian name.
Blac Chyna and Rob got engaged in April after three months of dating and welcomed daughter Dream in October.Rob's family was initially skeptical of the match, but sources told E! News the trademark conflict is "just business."
"Their trademark attorneys automatically oppose anyone trying to trademark 'Kardashian,'" an insider said. "Everyone loves each other."
Blac Chyna, who shares 4-year-old son King Cairo with Tyga, denied lingering rumors of a feud in the September issue of People.
"We've all talked, I've met up with Kylie," she said at the time. "Everybody is mature. We're not holding onto grudges. We've moved on."
