Yammo thought they were both dummies, though in the best possible way. She'd been ambivalent about Link's involvement in their child's life; she had no problem with him being there, and Zumi had wanted it, so she was happy to go along. Link seemed like a good man, and unlike many men out there, had cared enough to come looking for them to see if he was needed. That put him a number of notches above anyone she could've found herself at a later time.
And the fact that he was shutting the door on any semblence of a personal life for the sake of a woman who clearly meant the world to him told her that she and Zumi didn't have to worry about him changing his mind later and trying to force himself in where he wasn't wanted, which added a few more notches between him and those other potentials out there.
It definitely earned him those points he'd been losing back, that was for sure. Especially with the unnerving explanation of his memory problem. That must've been terrifying to go through. Maybe she'd ask him about it once they were settled in at Hateno and he had time. She didn't know what all duties he had to the queen, now that she was back and the job of Defeat Ganon was done. But it was certainly a story she'd like to hear, and she'd bet a couple hundred rupees that Zumi did too. And if Zumi were going to be part of the queen's life the way Link was asking her to, the queen's side of the story was probably one they were going to be getting, too.
But with Link's obvious discomfort with the subject of why he was saying no, and Zumi's attention on his request, it was falling to Yammo to bring up a few issues.
"I hate to be the practical party pooper," she said, "but we should probably get our stories straight." She nodded at Zumi, who let go of Link enough to turn to include Yammo in the conversation. "She just said donor, but is that actually an acceptable alternative? Or should we just lie wholesale? It's going to look a little strange either way we do it. The timing makes donor a bit of a stretch, but I'm not sure how else to explain why you came looking for us to tell us about Hateno in the first place."