We'd like to think that these conversations take place 'in camera' before they're reenacted in front of a camera in the name of 'entertainment'...
A source speaking via The Daily Mail said the following happened when Bruce Jenner sat Kourtney, Kim, Khloe, Kendall and Kylie down, while Keeping Up With The Kardashians was being recorded:
"He literally started the conversation with, 'Hey, guys, I'm becoming a woman, but I'm sure you probably already figured that out'... There was so much speculation, and they were all wondering about the truth. Bruce had to address it with them. He got a little emotional, but it wasn't a jaw-dropping conversation. It's a surprise to the girls that he's doing this at 65... They want nothing more than for their dad to enjoy the life he wants to live."
Bruce is said to have told his family to simply say, "Bruce is in a very good and happy place," if they were asked about him.
The episode in question, episode 13, will reportedly air on E! on March 15th. Bruce's transition will also be documented via his spin-off show. Obvs.