Having recently acquired lots of photos of varying ages, some with ID on the back and others not, I can understand your dilemma.
Some of the photos were marked in pencil on the back, which sounds OK, except that it was a hard pencil and the writer pressed rather hard. There are pressure marks

Other photos have recently been marked with identification - in blotchy biro which has then transferred itself to the photo surface underneath it in the pile

I have been scanning them and adding the id to them in a spreadsheet which describes the photo, its location in an album (if that is the case). It is time consuming to say the least.
Previously with large groups, I scanned the photo, printed it and then imported it into Word and added vertical lines to each face, printed it and then wrote the name of the person against the line. Useful if you can then get some other member of the family to confirm the ID or give their own version.
I'm sure there must be other ingenious ways of doing the same thing.
Nell