Deirdre Lawless, a sister of newly-elected Aontú TD Paul Lawless, has been selected to replace him on Mayo County Council.
Deputy Lawless was elected to Dail Eireann just months after winning a council seat in June.
Due to the abolition of the dual mandate, Deputy Lawless ceased to be a councillor as soon as he was elected to the Dáil.
His sister, who is a secondary school teacher based in Claregalway, was selected by Aontú party members to replace him on the council.
Deirdre Lawless has been telling Midwest News that going into politics has been on her radar for some time now.