The FAI may have to fight off a challenge to the restart of the 2020 League of Ireland season from unhappy clubs.
There is a charge from one outfit that the format for the rest of the campaign is "grossly unfair" and that they were "mugged".
In response, the body which represents LOI players has called on clubs to back off from any legal challenge which could cause further delay to a season which is due to resume on July 31, with a shortened format of just 18 games.
Nine of the ten Premier Division clubs had wanted the promotion/relegation playoff removed to ensure that only one club could be relegated.
But a narrow majority of the 19 league clubs voted to retain the status quo, including a playoff, a decision then ratified by the seven-member National League Executive Committee. That decision also has to get the ratification of the FAI board.
Niall Quinn, Interim Deputy CEO of the FAI, said the chosen format was "the least disruptive of the four" options.
Quinn added: "What it means for football is that there is clarity in the air now."
But the process, and the threat of two teams in a 10-team league being relegated has caused alarm among top-flight clubs.
Delegates from the Premier Clubs Alliance held a conference call late last night to discuss their next step. "There is a lot of anger at how this was gone about," one senior official said.
Sligo Rovers issued a statement last night saying the decision was "grossly unjust". They do not see the matter as concluded.
Sligo treasurer David Rowe added his club had been "mugged" as he criticised the decision-making process and the role of the NLEC. "This has a bit to run for sure," he said.
PFAI General Secretary Stephen McGuinness said: "We would plead for no more legal action as was mooted in the past," he said. "I would encourage clubs to accept the decision."