4.—(1) Subject to the following provisions of this paragraph, where the Authority is required to make a property arrangements scheme, the terms of the scheme shall be such as the system operator and the relevant existing transmission licence holder may agree or, if they fail to agree, as the Authority may determine.
(2) The Authority may not include in a property arrangements scheme provision which would adversely affect a third party unless it determines that it is necessary or expedient for implementation purposes for the provision to be made.
(3) Where the Authority does include in a property arrangements scheme provision which would adversely affect a third party, the Authority shall determine whether the scheme should include provision for compensation and, if so, what that provision should be.
(4) A property arrangements scheme shall not provide for any provision to come into operation before the end of the period of 21 days beginning with the day on which the scheme is made.