Whom should I complain to regarding old attorney misconduct while in bankruptcy court?

You normally need to file a complaint with the state bar. The process in each state may be a bit different, but the idea is to file the complaint with the bar in the first instance. The state bar may investigate the matter, especially if it is not purely a fee dispute. If it is primarily a fee dispute some state bars will refer the matter to a local grievance committee. I don't believe you can make a blanket assumption that the committee would not fairly handle the grievance. If you're going to make that assumption, just save your time. One other matter. You mentioned a bankruptcy. If the claim - to the extent one exists - predated your bankruptcy case, it would technically be a claim that should have been scheduled. Now you may not have known about it at the time, but generally claims that existed on the date you file are considered property of the bankruptcy estate. And, if the claim is not scheduled it has never been administered. May need to reopen the case to schedule it. If the trustee re-closes the case then the claim belongs to you.

The Greivance Committee is not an old boyd club. However, they do not get involved in billing disputes; instead, those tend to get referred to the Court's arbitration program. Your bankruptcy might compicate things as you may no longer be the actual owner of the claim as I suspect it is part of your bankruptcy estate.

The State Bar of New York has a procedure to hear such matters.