The magnetic divertor structure in a modular stellarator has been predicted to change with the addition of an external vertical magnetic field. The diverted flux is expected to emerge predominantly on the inside of the torus when a vertical magnetic field which shifts the magnetic surfaces towards the inside is applied, and vice versa. The prediction has been verified using probe arrays located in the divertor regions. In addition to the redistribution of diverted particle flux, the distance a field line travels from the separatrix until it reaches the wall has been predicted to increase for each of the magnetically altered cases. The formation of magnetic island chains beyond the separatrix has been found to be responsible for the increase.