So, I have a job and I created a custom graphic for it. No charge to the customer. They want that also on a shirt embroidered. I alter the graphic to accommodate and send to be digitized. I charge the customer for the digitizing. If they want the file, they have to pay for the original artwork first as the digitized version is a derivative of my original art. If they provided the camera ready art or they hired and paid me to create their design and I had it digitized and charged a digitizing fee then yes, they would be entitled to the file.