DUP leader Ian Paisley's daughter Rhonda is taking a case against her father's party in a sex discrimination action.
Ms Paisley is taking the case over her failure to get a job as policy officer in the DUP's policy unit last year.
The Democratic Unionist leader and other senior members of the party are named in the case being brought by Rhonda Paisley over a failed job application. Ms Paisley claims she did not get a position within the DUP's policy unit last year because of her gender.
A senior party source admitted tonight: "Everybody is amazed she is going ahead with this. It came completely out of the blue because she is very close to her parents, although it has not affected their relationship."
She was one of several candidates who applied last year to join the six-person unit which deals with drafting responses to consultation documents and drawing up policy on parliamentary issues.
Even though the Office of Industrial Tribunals confirmed they had received notification of the case, the hearing is not likely to be scheduled until sometime next year.
Earlier a party spokesman said: "We are content with the person who did get the job.
"It's all in the hands of our lawyers and we are not going to be distracted by this from the bigger issues."
It is understood a man with no connections to the party was appointed as a policy officer following the recruitment process.
But Ms Paisley, who has previously worked for her father at the European Parliament when he was an MEP, has lodged a case at the industrial tribunal offices in Belfast.
A former member of the city's council, she lives at home with her father and mother, Eileen.
The case has been taken against Alan Ewart, the party's chief executive, but also names Mr Paisley, the North Antrim MP.
DUP deputy leader Peter Robinson and fellow MPs Nigel Dodds, Gregory Campbell, Jeffrey Donaldson, Sammy Wilson, Iris Robinson and William McCrea have also been named along with MEP Jim Allister and Ms Paisley's brother, Ian Paisley Junior, a member of the Northern Ireland Assembly.