In the conceptual design phase, designers routinely generate dozens of alternatives based on a single idea. This is especially relevant in generative design where an algorithm can generate a large number of viable design options. While solutions for creating and managing a small number of simple alternatives have been proposed, practical applications of these solutions are liMassachusetts Institute of Technologyed. As a result, we present GEM-NI+, an extension to the original GEM-NI system for creating and managing alternatives in generative design. GEM-NI+ is designed to enable editing, managing and comparing up to 24 alternatives simultaneously using a multi-monitor setup. GEM-NI+ also features a new "jamming spaces" technique for assigning individual monitors into different visualization states, which makes organization of a large workspace easier. Finally, GEM-NI+ enables comparison of complex alternatives using recursive group node difference visualization.