When a merge occurs in Luminate Online, web services removes the master record and all its related records (donations, registrations, etc.) from the web services partition. It then adds the master record and its related records back to the partition. The non-surviving records and its related records are removed from the web services partition and the related records, such as donations, are added back to the partition under the ownership of the surviving master record. The timestamp of the removal and addition to the partition will match the merge time.

This means that any time constituent records are merged in Luminate Online, their donations, registrations, etc. will come down as both GetIncrementalDeletes and GetIncrementalInserts. In order to process this correctly in your offline system, you could remove the records that came down in a GetIncrementalDeletes call and then insert them again based on the GetIncrementalInserts result, effectively reparenting the records to the surviving constituent.