Bristol and Cheyenne are about to have their Teen Mom inauguration -- and the young moms just got a warm welcome from Amber, Catelynn and Maci.

"We're grown up now!" Maci declares in the clip above, as she embraces Bristol for the first time.

But when it comes to being a part of the long-running docuseries, Amber has a few words of wisdom for the newbies.

"You guys are gonna be able to help so many people with your stories now," the mother of two tells Bristol and Cheyenne in the clip.

How does Bristol relate to Amber, Cate and Maci? And what emotion would Cheyenne use to describe joining the "Teen Mom posse"? Watch the five women open up as they exchange hugs and tell their tales in the video, and do not miss them when Teen Mom OG begins on Monday, October 1 at 9/8c.