4. Where provision as respects any length of highway is contained in an instrument made, submitted or published in draft before the appointed day under any enactment and on and after that day parts of that length are situated in the areas of two or more authorities so that, if provision had been made on or after that day as respects that length, separate instruments made, submitted or published in draft by each of those authorities would have been required, then—
(a)the instrument shall have effect on and after the appointed day as such number of separate instruments as would then be required for that provision, each instrument relating to the part of that length of highway situated in the area of one authority and containing references to that authority instead of references to the authority by whom it was made, submitted or published in draft, and
(b)if the instrument is an order or scheme in relation to which some, but not all, of the necessary procedural steps have been taken before the appointed day—
(i)any notice given or published and any other document made or issued in connection with the order or scheme before that day shall similarly have effect on and after that day as such number of separate notices and documents (each containing references to the authority first mentioned in (a)) as may be requisite;
(ii)any remaining procedural steps required to be taken by the authority by whom the scheme was made, submitted or published in draft may be carried out separately by the several authorities concerned; and
(iii)the orders and schemes as made, confirmed or approved shall (so far as practicable) reflect the division into separate instruments.