Former Irish presidential candidate Dana Rosemary Scallan has denied claims by her sister and a niece that she defamed them, the High Court in Dublin has heard.
It arises out of a TV interview in which Ms Scallon was asked about allegations of sexual abuse against her brother John.
Susan Stein and her daughter Susan Gorrell, both living in Iowa in the US, have taken separate High Court actions alleging the Londonderry-born singer defamed them during the interview broadcast in October 2011.
Dana, they claim, made statements that meant both women maliciously made up claims Ms Gorrell was sexually abused between 1971 and 1981 by her uncle, John Brown. They claim the allegations of abuse are true.
Mr Brown (62), of Bracknell, Berkshire, England, was cleared in July 2014 of charges of indecent assault on two girls aged under 13 and 16 at several locations in Northern Ireland and England in the 1970s and 80s.
He denied all the claims against him and also denied claims that Dana helped him cover up the allegations.
The 1970 Eurovision Song Contest winner, now living in Co Galway, denies defamation.
Accompanied by her husband Damian, Dana was in the High Court yesterday for the opening before Mr Justice Robert Eagar of her pre-trial application for orders requiring the plaintiffs to provide security for her legal costs if they lose their actions.
Oisin Quinn SC, for Dana, said she had a "full and thorough" defence to both cases, but believed the plaintiffs would be unable to meet her costs should they lose.
The "sting" of the plaintiffs' claim, he said, was that words used in the interview by Dana, who had not named the plaintiffs, meant they were lying about the allegations of Ms Gorrell being abused by Mr Brown and had maliciously made up the claims.
Her defence to these cases includes denials the words in her interview meant what was alleged, counsel said.
In opposing the security for costs application, both plaintiffs contend their case was in the public interest.