Layman's guess and no clue of NY specific issues:
The fact that an heir requests an accounting does not mean said request will be granted, but lets assume it is granted:
Again my lay guess, a FORMAL accounting means a full blown accounting from square one which may be the date of death or date you took over, but again my guess is date of death so it would include any activities of any prior administrator as well , and up thru the current date, and that it means an accounting conducted by a CPA or attested to by a CPA --English translation=Expensive and daunting especially in your fact pattern!
But its not the heirs fault you failed to provide an accurate annual update to the score card is it?
Apparently on the other hand, if you have been providing decent updated and/or the applicants request for a FORMAL account is deemed to be frivolous by the court the NY court can make the applicant pay the costs!
Again, my lay guess
1. If you have been remiss in providing updated, be prepared to be order to provide a fancy formal full scale report.--at estate expense of course
2. If you have not been remiss, go get counsel, at estate expense of course, and defend vigioursly that a formal accounting is not necessary in your fact pattern.
3. Given the massive expenses involved, work it out with the heirs, who probably does deserve a decent review of all activities since square one, and seek to dealy formal hearing---the intent being to withdraw once a decent accounting has been provided.
&nbs... 3.1 There may be a difference--if you have merely been sloppy and slow--you might be able to convince heir to wait a modest time until you get it done--but speed matters BUT if I were the heir and I had reason to suspect you were self dealing or pocketing funds etc, I would not agree for just you to come up with answers, I'd want an independent audit.
&nbs... 3.2 Lets asssume formal route costs estate $25,000----now tell me what route is more cost effective?
3.3 Keep in mind that the heir for the attorney has a bit of a self serving motive called $$ to make you dance and keep dancing