Man, wife and sister: A heartwarming union

VIDEO: Man, Wife and Sister: A Heartwarming Union

This one is a keeper.

Earlier this year, Will Seaton showed there are still many good guys out there. When Seaton decided it was finally time to pop the question to Ashley Schaus, there was one person he had to ask a very important question. No, not her father, but rather her sister Hannah.

Seaton asked Hanna to be his "best friend forever."

Hanna has Down's syndrome and diabetes, and when Seaton and Schaus started dating, Hanna was part of the deal, the couple told ABC News in June.

The couple got married on Oct. 7 and Hanna was there in a special role.

Wearing a white dress of her own, Hanna was a bridesmaid, but she was also dubbed the “Best Sister.”

Hanna also exchanged "best friend vows" with Will, WXIN reported.

“I promise to tell funny jokes. I promise to care for you. Thank you for being in my life,” Hanna told Will.

They also had a first dance together, to the Michael Bublè version of "You've Got a Friend in Me," WXIN reported.