They can have more than one use, can't they? The coins? Besides, not everyone who has or ever will have one knows all the things you do. And do you really think someone's going to walk up to you in the middle of the 12th Night Ball and announce, 'Oh, hello, Lucius Malfoy's son, I am the leader of an insurrectionist faction bent on bringing down the Lord Protector and all for which he stands'? Of course you haven't met them.

If you want to use the coins to get round her, try writing a message about that and see what happens.