1. Within sixty days after the original filing, a lienor may amend his lien upon twenty days notice to existing lienors, mortgagees and the owner, provided that no action or proceeding to enforce or cancel the mechanics' lien has been brought in the interim, where the purpose of the amendment is to reduce the amount of the lien, except the question of wilful exaggeration shall survive such amendment.2. In a proper case, the court may, upon five days' notice to existing lienors, mortgagees and owner, make an order amending a notice of lien upon a public or private improvement, nunc pro tunc. However, no amendment shall be granted to the prejudice of an existing lienor, mortgagee or purchaser in good faith, as the case may be.