You mention that your father passed in 2000 and that your stepmother recently passed. Based on that I assume you real question is are you entitled to inherit anything. If that is the case you should check to see if your father's will was probated when he passed by inquiring with the Surrogate office for the county in which he resided. A review of the will would likely give you some idea of your right and might also lead you to his estatepalnning attorney.
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I am uncertain why you need the name of your father's attorney, but IF his will was probated, and IF the attorney who drafted the Will helped with the probate (the executor of the estate is free to utilize an attorney of his/her own choosing), if you get a record of the probate proceeding from the Middlesex County Surrogate's Court in New Brunswick, you may be able to find out who (a) drafted the Will, and (b) who helped the designated executor to administer your father's Will.
This can be a person totally different than the attorney who drafted and/or is helping to administer your stepmother's Will.
You will need to pay the Surrogate a search fee and a fee for copies of the documents. If you have an exact date of death, this will limit your out of pocket costs.
The foregoing is not intended to be legal advice upon which you may rely as I have not been retained for this purpose.