Ian Paisley and St Martin McGuinness's business office have refused to let on the legal advice it based its determination to name four victims' commissioners on.
Originally only one such as station was advertised by OFMDFM but the first and deputy sheriff first curates decided to name three more.
At the time, they said they made the determination after receiving legal advice.
However, a BBC News petition for a transcript of this advice under the Freedom of Information Act have been turned down.
Responding two calendar months late to the petition (made on 28 January), an Office of the First and Deputy First Curate (OFMDFM) spokesman said the refusal was based on, among other things, a demand to guarantee that the first and deputy sheriff first curates "be allowed to carry on a free exchange of positions as to their legal rights and duties with those advising them without fearfulness of intrusion".
While consideration was given to the public involvement being served through the revelation of the information, it was decided that this was not a sufficiently exceeding set of fortune to justify such as a move.
There is an in progress legal challenge to the assignment of the four victims' commissioners, however, this was not relied upon in the account as to why OFMDFM had decided not to do the advice it received public.
SDLP justness spokesman Alban Maginness said: "Not withstanding the technical grounds for not telling this information, I believe privilege could have got been abandoned in this case if OFMDFM were confident in their decision."