(a) Except as provided in subsection (b) of this section, the parties to an agreement may amend the agreement by mutual consent.

(b) (1) The parties to an agreement may not amend the agreement unless:

(i) there has been a public hearing on the proposed amendment; and

(ii) the district council or County Executive, as appropriate, approves any substantial amendment.

(2) A county planning board may not amend an agreement unless the county planning board determines that the proposed amendment is consistent with the Commission’s general plan.