Notwithstanding the provisions of paragraphs 1 and 2 of this Article, a Member which has availed itself of the provisions of paragraph 4 of Article 2 may, for as long as it continues to do so, substitute the ages 12 and 14 for the ages 13 and 15 in paragraph 1 and the age 14 for the age 15 in paragraph 2 of this Article.