The three key officials judged at fault by the Charity Commissioners cannot easily be dismissed, according to advice from the group's lawyers.
They have warned the National Confederation of Parent Teacher Associations that any attempt to sack the trio, who have been at the centre of the long-running dispute, could lead to expensive litigation which the NCPTA is likely to lose.
Winkworth and Pemberton, solicitors for the NCPTA, is investigating how the officers were appointed.
The Charity Commission believes the three officers, all former trustees, may have benefited from their position of trust in being appointed to their jobs with the NCPTA. They dispute this. It has also accused the confederation, which represents the parents of children in 11,500 state schools, of running up large hotel bills and expenses.
The commission wants Margaret Morrissey, press officer, Andrew Smetham, treasurer and Belinda Yaxley, membership secretary to resign and pay back thousands of pounds worth of salary.
Legal advice obtained by the NCPTA said the officers had fulfilled their contracts "admirably" and that there were no grounds for dismissal "apart from the alleged breach of trusts".
Winkworth and Pemberton warned that the NCPTA would have to be very sure of its grounds before dismissing them, and said it should be assumed they would start proceedings for unfair dismissal.
And it said: "It cannot be in the best interests of the NCPTA that it should embark on a course of action which will inevitably lead to expensive litigation which, on the facts as they are presently known, the NCPTA is likely to lose.
"Further, the course of action advocated by the Charity Commissioners will inevitably lead to a breakdown in industrial relations between the remaining staff and the executive committee and will lead to recrimination and schism within the membership."
And in the latest twist in the saga a past chair, who is the co-founder of a rival organisation representing 2,500 schools throughout the UK, will step into the fray today.
Larry Goodband has been asked to provide information to the law firm on the appointment of the officials.
The NCPTA has been dogged by in-fighting for decades, some of it conducted by anonymous faxes sent to newspapers. In the past year, its national executive has removed two trustees - Sandi Marshall and Sean Rogers, the chair-elect - and a chief executive left after just three months in post.
The inquiry into the officials' appointment began last month and involves at least 15 trustees who ran the organisation in the early 1990s. It has been instigated by Winkworth and Pemberton.
The Charity Commission has granted an interim order which sanctions the continued employment of the three officials but has pledged to "monitor the issue".
Judith Wood, chair of the NCPTA, said she was hoping the commission would grant a special order for the three members of staff to stay in post.
But Mr Goodband's evidence to the solicitor may prove significant. On the appointment of Mrs Morrissey, he said: "I did voice my strong concerns at the time of the appointment." Mr Goodband, who was chair of the NCPTA in 1992, said there was no sense of sour grapes on his part, and added: "I am anxious to help. I understand these problems are severe."