We think these photos show his sister and her husband. We know they were developed in a photo studio in Cernauti as this is stamped on the back.
There is writing on the back of the photos in German:
The writing mentions Herr (Andreas?) Duda who we think must have been his brother-in-law.
Then there are some photos of a workshop, which seem to have been in exchange for the ones he sent them of where he was working in Brussels.
We don't know who any of the people are, or what the workshop was for. Jules registered himself with the profession of metallurgist.