INSIDE EDITION's Exclusive Interview With Jaycee Dugard's Long Lost Sisters

Jaycee Dugard has missed a lot during her 18 years in captivity. In fact, she has half-sisters whom she never knew even existed.

Brittney and Sarrah Slayton, now 21 and 24, are the daughters of Jaycee's biological father, Ken Slayton.

Slayton is a retired truck driver who lives outside of Los Angeles and had a brief relationship with Jaycee's mom, Terry. He has never met Jaycee.

When Jaycee disappeared, his two younger daughters weren't told that their big sister was missing.

"When she was abducted, obviously, we were too young to understand what happened," said Brittney.

Then came the astonishing news that Jaycee was alive, and had been kept a prisoner in the backyard of the monster Phillip Garrido's home for all those years.

Now, Jaycee's other family hopes they can welcome her and her two daughters into their brood some day, but they say she hasn't responded to their attempts to get in touch.

Jaycee has been healing at a top secret location in Northern California. Since she's coming forward with her remarkable story, her half-sisters hope she'll consider meeting them.

"I want her to know that we're here for her, when she's ready," Brittney said.