GANGNEUNG, South Korea — Matt and Becca Hamilton, Olympic curlers from Wisconsin, had a bad habit of turning their matches into soap operas. They nitpicked each other. They argued. Sometimes they even yelled.

None of this would have been such a big deal — they are siblings, after all — if they had not been doing it out on the ice during competitions, in full public view. It was a recipe for disaster, and it was especially hard on their mother, Cathy, who just wanted them to get along.

“We bickered quite a bit,” said Matt Hamilton, 28. “We both hate to lose, and we were losing a lot.”

Now, they are competing as medal contenders for the United States in mixed doubles at the 2018 Winter Olympics. To get there, they had to transform their on-ice partnership, starting with a heart-to-heart conversation last March.

They agreed on a handy way to deal with disagreements on the road to the Games.

“We came up with a safe word,” said Becca Hamilton, 27, “so if things were starting to go bad, we’d say that word and that meant we had to drop everything.”