My point is, the tax preparer has a duty to file a complete and accurate tax return, regardless of legal battle between trustees, officers, partners, spouses ..etc.
Okay so we go ahead and file for 2019, the estate is closed; legal and accounting fees are paid; and all the money is distributed.
Then a letter from the IRS turns up with a demand to file for 2016 that nobody happened to mention before. Now who are the fingers pointed at?
It is not going to be me unless I have found a case law exception for constructive receipt due to failure of fiduciary duty and have been compensated for it.
As joanmcq mentioned, the sibling have been fighting since 2008, so don't expect anything to change in that department. Some could be in it for the battle and could care less about the money.