Teachers' union the NASUWT has admitted some schools it said would have teachers striking will not be involved in its industrial action.
The union said its list of schools was based on the geography of the Belfast and Newtownabbey area, but that the vast majority would have NASUWT members and would be impacted by the strike.
It comes after angry school heads criticised the union for including them on its lists of those taking part in strike action later this month.
Large numbers of teachers are expected to strike n a dispute over pay, working conditions and job security.
The NASUWT, while not specifying an exact date for this month's action, did list some 232 Belfast and Newtownabbey schools said had members which would be called upon to strike.
It warned some would be forced to close because of the numbers involved.
However, a number of those listed contacted the Belfast Telegraph to say they had no members in the NASUWT and therefore would not be impacted.
One head said that as she was the sole member of the teaching staff and a member of Ulster Teachers' Union - she could say for a certainty her school would not be involved.
"We have had to field calls all day from parents wondering what is happening because of this," She told the Telegraph.
"As the unions are all too aware, we are overworked and could do without the extra work of having to deal with incorrect information being put out there.
"And it is all down to the information from the union - they are just wrong.
"It just looks like they have listed all the schools in the area."
The NASUWT was unapologetic. It admitted it listed schools in the geographic area and conceded schools listed may not be involved in the strike.
General secretary Chris Keates said: "The NASUWT is taking a rolling programme of strike action and has published a list of all schools in Belfast and Newtownabbey which is the geographical area that will initially be affected.
“The schools that will be affected are the ones that have NASUWT members, which is the vast majority of those schools.
“It should be borne in mind that union membership is confidential, and members of trade unions are protected by law from workplace intimidation.
“It begs the question how some principals claim to know they have NASUWT members, unless of course they are acting in breach of the law by requesting teachers to declare their union affiliation.
“The NASUWT will not hesitate to take action, including legal action, against any school that seeks to intimidate any member of the NASUWT.”