Rhonda Paisley is taking a sexual discrimination case against the Rev Ian Paisley and the DUP because she failed to gain a job in the party's policy department.
Ms Paisley, who is no longer a member of the DUP but still lives with her parents, is claiming sexual discrimination against the DUP leader and other officers of the party including her brother, Ian jnr, who said the family would not be commenting on the matter.
The North's Equality Commission is supporting Ms Paisley, an artist and former Belfast city councillor, in her claim. The DUP is defending the case which is listed with the Office of Industrial Tribunals.
Ms Paisley is claiming she failed to be appointed to a senior post in the DUP's policy department last year because she is a woman. The job went to psychiatrist Dr Philip Weir, a former Young Ulster Unionist who defected to the DUP.
While the case seems highly unusual and perhaps embarrassing for the party, it does not appear to have caused serious friction within the Paisley household. Earlier this year Ms Paisley described her father as "a bit of a softy" in an interview with the Belfast Telegraph.
She told the paper: "My father also believed in discipline in the family and we all knew what the house rules were when we were growing up. But I actually think that makes a person gentle."
One of those listed on the DUP officer board, whom Ms Paisley is challenging, is Paul Berry who faces potential party disciplinary action against him in relation to his private life. The party is investigating a report in the Sunday World that Mr Berry met a male masseur at a Belfast hotel and that a sexual encounter took place. Mr Berry, who is suspended from the party, denied the allegations and has threatened legal action.
Earlier this month, Mr Berry won an injunction blocking the party proceeding with a disciplinary hearing against him. The party is appealing this decision.