Her admission was surprising. If the roles were reversed, Hermione would never tell anyone where Ollie was. Occasionally she wasn't a completely dreadful mother. It truly was an act of trust. Or, it was an elaborate lie designed to wedge Hermione into a trap. Either way, she wasn't about to head off for Edinburgh to find the child. As far as she was concerned, she didn't exist and there was no reason to find her.