Use a simple identifier photo for each subject. The easiest workflow is to have each person fill out a form or sign-in line with their name and email, then photograph that form immediately before photographing them. That creates a visual marker in the sequence, so every image after the form belongs to that subject until the next form appears.

You can also have them hold a whiteboard or paper with their details for one frame. If your camera shows image numbers/file names on playback, write one reference image number on the sign-in sheet so you can locate that person’s set later.

For extra safety, add an end marker after each person or group, such as a blank sheet or black card, especially if you might interrupt the sequence with unrelated shots.

This is a common low-tech digital workflow because extra frames cost nothing and also give you a backup record if the paper forms get lost or out of order.