When you change your reporting organisation, the change affects the Activity Identifier. Since Reporting Organisation Identifier is the first part of an Activity Identifier, the newly published Activity Identifier will have a different identifier than those activities that have already been published (Activity Identifier of published activities cannot be changed).
The IATI standard requires activities created under the same organisation to have the same Reporting Organisation Identifier for data consistency. ID mismatch will raise the question of whether or not the activities are of the same organisation.
So, it is crucial that the changes on one platform reflect on another. As far as possible, consult/inform with the IATI team and AidStream team while making changes in the information.