World number 46 Thompson will be competing in her seventh consecutive Solheim Cup, Kupcho (53) will wear the red white and blue for a third time and Schmelzel (61) makes her debut.
The trio joined automatic qualifiers Nelly Korda, Lilia Vu, Lauren Coughlin, Ally Ewing, Allisen Corpuz, Megan Khang, Andrea Lee, Rose Zhang and Alison Lee for the September 13th-15th Solheim Cup at Robert Trent Jones Golf Club in Gainesville, Virginia.
Thompson, in what could be her final Solheim Cup given she has said she will stop playing full-time competitive golf after the 2024 season, has a 9-7-7 record in the event while Kupcho has a 2-3-2 career record.
"Lexi was probably the easiest pick to make of these three, with her experience," Lewis said. "I know what Lexi can do at a Solheim Cup and that definitely helped her get a pick.
"She's somebody who is going to help the team out a lot, on the golf course and also off. With her experience, everybody on the team's going to be watching what she does to try to learn from her. I am very happy to have Lexi back."
The United States lead Europe 10-7-1 all-time in the Solheim Cup, which is a biennial competition between teams of 12 players and follows the same format as the men's Ryder Cup.
Europe have held the trophy since 2019, having earned a tie last year in Spain to retain it. The Solheim Cup is being held in back-to-back years to get on an even-year schedule.
