He knows

Sana: *hugs her* he does realise I can telaport to right ?

Nightmare: that's enough *grabs me again and teleports away*))*Types stuff into the item and teleports back to sana,Chara and frisk*

Sana:Actually u don't need dat to tellaports I gave u magic to telaports along time ago

Nightmare: Uh..))No you never gave me this item,I've made it myself-