Fragment merger dynamics in a collapsar-disk-like arrangement. Shown are three different configurations, consisting of one initial cluster (top row), two clusters (middle row), and three clusters (bottom row). Each panel shows the orbital tracks accumulated up to the time t / M = ct/r_g printed in the upper-left corner, using the same viewing angle in all panels. Here r_g = GM/c², where M is the total initial mass of the system. The dynamics occur almost entirely in the midplane. Colored curves trace the previous motion of the respective compact objects, while black spheres mark their instantaneous positions; the sphere radii are scaled by mass to visualize the changing masses after mergers.