South Dakota's US Attorney is flying to Spain with his wife and two of their children.
Brendan Johnson and his family have searched for seven years to find the sister of his Ethiopian-born son, 15-year-old Peneal.
The Johnson's adopted Peneal, who goes by Penn, along with 17-year-old Trualem in the summer of 2007.
But ever since that day the Johnson's have been looking for Peneal's biological sister - and now they've found her in Spain.
"It's probably the most exciting thing to happen in our family," Jana Johnson said.
The O'Gorman freshman was adopted from Ethiopia seven years ago.
During the trip, the Johnsons discovered Penn has a younger sister who was adopted two years earlier.
His birth mother asked the family to reconnect the children, who weren't supposed to be separated.
"She didn't know where her daughter had gone either," Brendan said. "And so part of this trip is also about fulfilling a promise that we made to Penn's mother seven years ago.
After gaining limited information from the Ethiopian government, the family did an internet search and with the help of social media, found Penn's 13-year-old sister in Madrid.
"We ended up using Google, email and Twitter accounts and eventually wound our way to the family," Jana said.
Penn says he's excited and a little nervous to meet his sister after living years apart and continents away.
"Our feeling is, not only did we find Penn's sister but almost as if we found another daughter," Brendan said. "We are hoping that the two families can continue to meld together."
Penn's sister's family also was looking for him but hit a dead end several years ago.
Once the Johnson's reached out, they had a response within 15 minutes.