The citizenship saga which has engulfed Australian politics will return to the High Court in Canberra.
Chief Justice Susan Kiefel is presiding over a directions hearing on Friday ahead of a full court hearing in October.
Deputy Prime Minister Barnaby Joyce and fellow Nationals MPs Matt Canavan and Fiona Nash are among the seven MPs who could face disqualification from parliament.
Former Greens senators Scott Ludlam and Larissa Waters will also have their eligibility tested, although they resigned after learning they were New Zealand and Canadian citizens respectively.
South Australian senator Nick Xenophon and One Nation's Malcolm Roberts round out the seven MPs who will face a full court hearing from October 10.
Senator Xenophon has confirmed he is a British overseas citizen by descent, as his father was born in Cyprus when it was still a colony.
He remains confident he has a very good legal team and a strong case.
"We're in uncharted waters here," he told ABC radio.
"I had no idea that I had some obscure form of British citizenship."
Senator Xenophon joked he was thinking of cooking some octopus and lamb on a spit on the High Court forecourt ahead of the October hearing.
"I'm not sure whether my barristers would appreciate that."
Queensland senator Roberts faces questions over whether his UK citizenship was renounced before he nominated for election.
Under section 44 of the constitution a person is incapable of being elected to the parliament if they are a "citizen or entitled to the rights or privileges of a subject or a citizen of a foreign power".
While Senator Canavan has stepped aside as Resources Minister after learning he was an Italian citizen, Mr Joyce and Senator Joyce have remained in cabinet.
Labor have attacked the Nationals leader and deputy leader for staying in their roles, arguing any decisions they make as ministers could be challenged in court if they are found to be ineligible.
Mr Joyce is a New Zealand citizen by descent, while Senator Nash has been advised by the UK Home Office she has British citizenship through her Scottish father.