Will Seaton not only married his wife, Ashley Schaus, Oct. 7, he also exchanged vows with younger sister Hannah, who has Down syndrome. (Tyler Roberts)

Encouraged by her sister Ashley Schaus, Hannah Schaus said her vows at an Indiana bed-and-breakfast as friends and family looked on.

But Hannah wasn’t the bride, Ashley was.

Ashley’s groom, Will Seaton, not only married his wife, he also exchanged vows with her younger sister, Hannah, who has Down syndrome.

“Hannah, I’m thankful that you’re my sister and my best friend,” Seaton said to Hannah as the wedding guests looked on. “I promise to take you fishing, tell you plenty of funny jokes and, most importantly, I promise to always look out for you.”

When the vows were complete, the pastor pronounced the soon-to-be in-laws “best friends forever.”

Since meeting Ashley at a car show in 2010, Seaton has always known that she was part of a package deal.

[‘I’m finally a weather girl’: Woman with Down syndrome fulfills a lifelong dream]

“Hannah will always have to be dependent, so it was one of those things where I was so glad [Seaton] went out of his way to include her,” Ashley said. “She’ll never be able to live alone. When my parents get older and can’t care for Hannah, she will be under my care.”

So in March of 2016, when the time came for Seaton to get down on one knee, he first “proposed” to Hannah, asking her to be his “best friend” and offering her a ring that belonged to the sisters’ grandmother.

“I had made a joke to him that Hannah and I are always together,” Ashley recalls. “I told him, ‘You’re going to have to marry both of us,’ and he took it seriously.”

Ashley said she didn’t want her Oct. 7 wedding to be focused on the typical material details, such as the venue, the dresses and the cake. Instead, she wanted her ceremony to highlight friendship. She wanted Hannah to have a special role in the wedding, as she will in their lives moving forward.

“When you get married, everyone comes with you,” Ashley said. “This is what marriage is about. It’s about friendship, bringing your family into the picture and going from there. It was wonderful. I know I can trust him with Hannah for the rest of my life.”

It rained, but the Schaus sisters, in their elegant white dresses and carrying marigolds and hydrangeas, still thought their day was perfect.

Ashley Schaus and Seaton shared their first dance to “Soul Mate,” followed by a first dance between Seaton and Hannah Schaus to “You’ve Got a Friend in Me.”

[A groom jumped into a pond during his wedding photo to save a drowning boy]

The wedding day was very special, Hannah said. The first dance was her favorite part, followed closely by smashing cake in her sister and Seaton’s faces.

After their story went viral, the Schaus family heard from many parents with special needs children who could relate and hoped their children would include their special needs siblings the way Ashley Schaus and Seaton have embraced Hannah.

“I wanted to share everything with Hannah. She was more than just a bridesmaid. I wanted her to feel like she stood out. We didn’t take anything away from the day, we gained,” Ashley said.

She now lives with her new husband in a house the couple built next door to the Schaus family home in Santa Claus, Ind., where Hannah lives with her parents.