Libertas has confirmed two of the party's candidates for the European Parliament have named relatives on their list of replacements.
Candidates nominate a number of replacements so that in the event of death or resignation of an MEP the seat can be filled without an election.
The party's candidate in the East constituency Raymond O'Malley has named two replacements his wife, Pauline, and his brother, Edward.
Party leader and North-West candidate Declan Ganley named his brother, Seán, second on his list of replacements.
However, a Libertas spokesman said Mr Ganley's primary substitute is Dr Chris Coughlan who has no blood relationship with Mr Ganley and who has 'an intimate knowledge of the economy and Irish business'.
Dublin Libertas candidate Caroline Simons has not nominated any substitutes.
The spokesman added that Libertas candidates have given a commitment to serve their full terms if elected and that the substitute provision would only be used in the event of an unforeseen tragedy.
