Bottom: the fraction of the integrated ALMA flux of SMGs in each AS2UDS ALMA map that is contributed by secondary and tertiary components (ranked in terms of their relative brightness) as a function of the deboosted flux of the corresponding SCUBA-2 source. The horizontal dashed line shows the median fraction of the total flux contributed by secondary SMGs for these maps, 34% ± 2%. There is no significant trend in the fractional flux density contributed by the secondary component as a function of the original SCUBA-2 flux density. Top: the filled histogram show the distribution of the deboosted 850 μm fluxes of those SCUBA-2 sources that have multiple SMGs in our ALMA follow-up maps, and the unfilled histogram shows the corresponding SCUBA-2 fluxes of the parent sample of all 716 single-dish sources. We also plot cumulative fraction of the single-dish sources with fluxes greater than S_SCUBA-2 that break up into multiple components, f_mult (S > S_SCUBA-2). This fraction increases with increasing single-dish flux.