Man Proposes to Girlfriend and Her Sister, Who Has Down Syndrome

Hannah Schaus, 15, has Down syndrome, and her older sister, Ashley Schaus, 23, will become her legal guardian when their parents get older.

It was twice the decision for this Indiana man, who not only proposed to his girlfriend, but also to her little sister.

Read: Girl With Down Syndrome Cannot Contain Her Joy When Boyfriend Gives Her a Promise Ring

Hannah Schaus, 15, has Down syndrome, and her older sister, Ashley Schaus, 23, has always been prepared to become her legal guardian when their parents are unable to take care of her.

So when Ashley and her boyfriend of seven years, Will Seaton, 25, started discussing the prospect of marriage, Ashley joked, “You never thought you’d have to marry two women at the same time.”

But, Will was happy to.

Using a simple ring Ashley and Hannah’s grandmother had given him, Will dropped down to one knee to propose to Hannah first, asking if she would be his “best friend forever.”

When the teen agreed, Will turned to Ashley and asked if she would marry him.

“He definitely goes out of the way for her so this was more than I could ask for,” Ashley told InsideEdition.com.

Bret and Brandie Photography captured both sisters' heartwarming reaction to the surprising double-proposal.

She said she and her little sister have always been close, and they do nearly everything together.

“When she was born, my parents told me she was going to be extra special because she had Down syndrome,” Ashley explained. “They were letting me know that I’m going to need to look out for her and protect her.”

Although she’s now starting a family of her own, Ashley is making sure Hannah feels included, especially when it comes to the wedding.

Read: 'It's So Exciting': Little Girl Tells the World That Down Syndrome Isn't Scary in Viral Video

‘We came up with the term ‘Best Sister,’” Ashley said. “She’s more than a bridesmaid but not obviously a bride.”

Hannah will even dance with the groom in a special song, “Best Friend” by Harry Nilsson, and wear a white dress for the big day.

“The happiness level is infinite, it’s not like she’s stealing anyone’s thunder,” Ashley said.

Watch: Couple with Down Syndrome to Celebrate 22nd Anniversary: 'I've Never Seen Love Like It'