Hi @ssmartt, we create a DIAObject at the time of the first DIASource. The second DIASource will associate to that DIAObject and the second alert will contain the history (with nDiaSources set to 2 as you indicate).
We’re confident this works for standard WFD visit pairs, but it will break down for images taken in rapid succession (whether due to marginal field overlaps or repeated images taken in the DDFs). The output in that case is a bit less predictable as it depends on pipeline and APDB performance. We expect we are going to need an end-of-night process to tidy up duplicate DIAObjects and other association issues, but we have not yet developed it.