§1. If the guardian, curator, or procurator who is necessary according to the norm of can. 1481, §§1 and 3 ceases from that function, the trial is suspended in the meantime.
§2. The judge, however, is to appoint another guardian or curator as soon as possible; the judge can appoint a procurator for the litigation if the party has neglected to do so within the brief time period established by the judge.
Source: Code of Canon Law (Vatican.va)