2. If the sending State refuses or fails within a reasonable period to carry out its obligations under paragraph 1 of this article, the receiving State may refuse to recognize the person concerned as a member of the mission. Article 10 1. The Ministry for Foreign Affairs of the receiving State, or such other ministry as may be agreed, shall be notified of: (a) The appointment of members of the mission, their arrival and their final departure or the termination of their functions with the mission; (b) The arrival and final departure of a person belonging to the family of a member of the mission and, where appropriate, the fact that a person becomes or ceases to be a member of the family of a member of the mission; (c) The arrival and final departure of private servants in the employ of persons referred to in subparagraph (a) of this paragraph and, where appropriate, the fact that they are leaving the employ of such persons; (d) The engagement and discharge of persons resident in the receiving State as members of the mission or private servants entitled to privileges and immunities. 2. Where possible, prior notification of arrival and final departure shall also be given. Article 11 1. In the absence of specific agreement as to the size of the mission, the receiving State may require that the size of a mission be kept within limits considered by it to be reasonable and normal, having regard to circumstances and conditions in the receiving State and to the needs of the particular mission. 2. The receiving State may equally, within similar bounds and on a non-discriminatory basis, refuse to accept officials of a particular category. Article 12 The sending State may not, without the prior express consent of the receiving State, establish offices forming part of the mission in localities other than those in which the mission itself is established. Article 13 1. The head of the mission is considered as having taken up his functions in the receiving State either when he has presented his credentials or when he has notified his arrival and a true copy of his credentials has been presented to the Ministry for Foreign Affairs of the receiving State, or such other 5