Call Jerry Uelsmann. Consider re-taking the picture with a slow shutter speed as the subject moves their arms or prepare to spend a lot of time and paper. I once printed four 4x5 negatives using one enlarger on a 16x20 paper for an Arts-In-Public- Places assignment. Each image was separate and had an unexposed grid separating them. I had to make masks and remove and replace the paper for each exposure. It took ten hours to come up with the result I sought.