What no one thinks to consider is....God-level Sanses.
I mean....Error, Ink, Fresh, and other powerful multiverse travelers being invited to join in on a meeting after Linda catches wind that Core! Frisk isn't mute, and doesn't go to school. Of course Ink excepts and drags his boys along for the ride (Error, PJ, and Gradient. Fresh just tags along to annoy Error and flirt with Jammy). I would please like a fic of this. If someone ever writes one, please send me the link. Here's some ideas...
Ink: Hello Ms. Linda! My name is Sans, but to differentiate between us and your Sans, you may call me Ink. This is my husband Error(points to Error), Fresh who came for some reason(points to Fresh), and my sons Paperjam and Gradient(points to the sweeties).
Linda absolutely freezes. Multiple Sanses...married to each other. Then she catches sight of Core, a telepathic, monochrome version of Frisk, and their wifey Blank, a white and red, also mute version of Frisk. She openly stares at the two strange children, before Gradient stands up for them.
Gradient: Stop staring at them like that. They're still human...mostly...
Linda proceeds to faint.