The Director may amend a certificate where in his opinion-
(a) there is an error on the face of the certificate; or
(b) it has become desirable for the certificate to extend to-
(i) proceedings;
(ii) other steps;
(iii) subject to regulation 6, other proceedings;
(iv) proceedings which may be taken to enforce or give effect to any order or agreement made in the proceedings in respect of which it was issued; or
(v) the bringing of an interlocutory appeal; or
(c) it has become desirable for the certificate to extend to any steps having the same effect as a cross-action or reply thereto, or a cross appeal; or
(d) it has become desirable to add or substitute parties to the proceedings in respect of which the certificate was issued; or
(e) it has become desirable for the certificate not to extend to certain of the proceedings in respect of which it was issued; or
(f) a change of solicitor or counsel is required.