They decide to ask Peatrice.

Deciding to stick with someone who knows more about what was going on anyway, Link told Fi that Peatrice would be the best candidate. Within an hour, they had arranged a meeting with her at her house at Skyloft. Once there, she looked from her completely stoic boyfriend to his seemingly normal sword spirit, then asked, "Something's going on, isn't it."

Link let out a sigh, then told her that he was in fact Link, and that his sword spirit, Fi was in his body. In order to switch back, they would need volunteers to switch bodies as well. From there, Fi explained her mathematically based plan, and Peatrice understood.

"Of course I'll help you, sweetie!" she told Link, smiling now that she could see her boyfriend's spirit in that body. "When it's time, I'll be ready!" Now that she was on-board, they needed to decide who would be their male candidate for swapping. Like Peatrice, Groose was involved enough that it would make sense for him to be a part of it. Then again, Fledge was such a timid young knight, he would be a good candidate as well, since he wouldn't say no. Pipit was also a possibility, and with his honesty and integrity he would be a fine choice.