100 portraits with names recorded - how to do, help!

I have a project I am going to work on this week.
At the beginning of a conference I need to take photos of couples/guests AND record their names. Next day I need to print the photos and mark them with the couples/guests names.

I am planning to take the photos, and:

have a blank sheet and i will ask them to fill in their names one after other, and
record a video of the whole portrait session (2hours) including audio where I also voice record their names and the photos I take.

Have you ever done something like this? I was thinking to record audio to the camera file but I have never done this before. I have a 5D mark Iv and a Canon r5. Is this a proper way to ensure all photos are assigned with the right photos? I just don't want to mix up the names and assign the wrong name to the photo.

Alternatively just have everyone write their name on a card and hold it up. Take a shot with the card then take the portrait shots.

Yes. A second shot with whatever identifier you want. If you have a slate chalkboard those are easy to deal with as the white writing on a black or green background is less likely to get blown out that anything on a white sheet

I did with the white board yesterday. Worked awesome! Thanks so much!!!!