1. A method for updating an event sequence, the method including: acquiring video data of a queue area from at least one image source; receiving a number of individual event requests from multiple subjects, each event request being received when a subject is located in one of multiple queues in the queue area; searching one of frames and at least one region of interest (ROI) in the frames of the video data for a subject located near at least one defined start points, each corresponding to one of the multiple queues in the video data; tracking a movement of each detected subject through the queue area over a subsequent series of frames; using the tracking, determining if a location of a tracked subject reaches a predefined merge point on the image plane where the multiple queues in the queue area converge into a single queue lane; in response to the tracked subject reaching the predefined merge point, computing an observed sequence of where the tracked subject places relative to other subjects already past the merge point and approaching an end-event point in the single queue lane; and, updating a sequence of the events to match the observed sequence of subjects in the single queue lane.