Caitlyn Jenner's eldest daughter thinks the former Olympian is "just nicer" now.

Caitlyn Jenner

Caitlyn Jenner

Cassandra Jenner admits she was previously estranged from the 'Keeping Up with the Kardashians' star, who was known as Bruce Jenner before undergoing gender transition, and says her "relationship with Caitlyn is much better than with Bruce, but we still have a lot of work to do."

The 34-year-old blonde beauty told PEOPLE magazine: "[We] didn't talk for years, and now we see each other every couple of weeks and talk on the phone, which I am grateful for.

"She's happier and more appreciative of her family. She is trying harder and there is a softness to Caitlyn that is new to me. I think part of that is that when someone is happier, they are just nicer."

Cassandra felt "so honoured" when Caitlyn recently invited her over for a girls' night in at her Malibu home in California because it was "such an intimate gathering after all these years."

She added: "I am pleased with how beautiful and comfortable she seems every time I see her. She seems to be having a lot of fun with it!

"There is so much more to being a woman than our external appearance. I am really looking forward to exploring that more with her."

Aside from Cassandra, Caitlyn has five other biological children from three previous marriages, including Kendall and Kylie Jenner, and four stepchildren, including Kim Kardashian West.