NY...If you haven’t talked to them they may be totally unaware of the problem. If you haven't perhaps initiating a casual and calm conversation about the buildings transfer of noise/vibrations and your chandelier rattling could help in finding a solution...at least making them aware of where your chandelier is under their floor. If it doesn't i'd replace the chandelier with something that doesn't rattle....old buildings or any ones without good unit isolation can cause lots of neighbor problems...good luck in finding a positive solution....