Probability distribution (normalized to unity) that N star clusters (excluding the cases with N = 0) are within 1 pc of the caustic (line of infinite magnification on the source plane) for the different realization of the position and rotation of the galaxy shown in Fig. 1. The histogram shows that if enough stars are present near the caustic the probability they are all in a single star cluster is P(1) = 25%, while the probability of them being in two clusters is higher (P(2) = 35% or P(2)/P(1) = 1.4). The probability of them being in more than one cluster (2 and above) is ∼75%.