Legal Question in Constitutional Law in New York

Has your sister given you a reason WHY she wants it appraised? The question is whether your mom gave you this painting of nominal value as a gift two years before she passed away. If it was a gift made during her lifetime, then the painting was already yours and is not a part of her estate (i.e., no appraisal required). If the painting was not a gift, but rather given to you by mom to hold for her, then it is a part of her estate and it would be fair to have it appraised if your sister is acting as the executrix or administratrix of mom's estate charged with getting that done. This answer is based on the very limited facts given. It would, of course, be better and more complete to meet with an attorney who can ask the right questions and find out all the details that could influence this answer.