The Disclosures Tribunal has heard it may be appropriate to look at contacts between the former Garda Commissioner and the Government during the current module.
This phase will look at whether false sex abuse claims were "inappropriately relied upon" by the former Garda Commissioner Noirín O'Sullivan to discredit whistleblower Maurice McCabe at the O'Higgins Commission.
Counsel for the Tribunal has said in its opening statement that communication on this matter in May and July of 2015 may be relevant.
The former Tanaiste has previously said she did not recall receiving a letter in May 2015 regarding the Garda legal strategy to discredit Sgt McCabe at the earlier inquiry.
The tribunal will only hear from one witness today, after which it will be adjourned due to the volume of information received in recent weeks.
The former Justice Minister and Garda Commissioner are both set to give evidence over the next fortnight.
The tribunal will also investigate contacts between members of An Garda Síochana and a number of other groups - including media and broadcasting personnel, the HSE, and the child & family agency TUSLA.
Noirín O'Sullivan scheduled to appear before the Tribunal on Tuesday and Wednesday this week.
Frances Fitzgerald is pencilled in for next Tuesday, while Sgt McCabe himself is expected to appear two days later.
The question of whether the former Justice Minister and Tánaiste knew of a legal strategy in relation to Sgt McCabe led to Deputy Fitzgerald's resignation from cabinet last November.
A full list of scheduled witnesses can be found on the Disclosures Tribunal website.
Reporting by Juliette Gash & Stephen McNeice