Article 3, section 2 states:
In case of the absence or impedance of the President, the Commission is presided over by the first of the Cardinal Members.
Article 9, section 2 states:
He [Secretary-General] takes the place of the President of the Commission when the latter is absent or impeded, except in what is determined in art. 7, n. 2.
Article 10, section 2 states:
He takes the place of the General Secretary when the latter is absent or impeded.