Two former DUP councillors joined Jim Allister's Traditional Unionist Voice party on Tuesday.
George Ennis and Terry Williams from Ards Borough Council signed up to the fiercely anti-Agreement party, bringing the total number of councillors to 18.
Cllr Williams, 54, left the DUP two years ago.
"I don't believe that you go to the front door and give a manifesto to people and go completely away from it," he said.
He is a retired senior social worker from Newtownards who has supported young people's projects in Russia and Romania. He was first elected in 2001.
Cllr George Ennis, 56, was first elected in 1993 and is a former mayor and Assembly member.
He had also previously left the DUP, whom he represented in the Assembly although it was suspended.
He is from Greyabbey and worked as a furniture restorer.
Mr Allister said: "Like many ordinary citizens these two men found the admission of terrorists to the government of our land shocking and wrong.
"Now that we have demonstrated the existence and viability of a party which holds tenaciously to the traditional unionist values which so many people rightly espouse, I believe we will see TUV becoming the natural home for more and more principled unionists.
He added: "Strangford is a strongly unionist constituency and as we build TUV it is great to have on board these two new councillors.
"I look forward to working with them and together with the local branch seeing the cause of traditional unionism flourish and grow in Newtownards and district."
© Press Association