how to load multiple periods of ownership data

Summary:

Is there a method or mechanism to load multiple periods of ownership data. Currently we either update manually period by period in the UI. Or load a flat file with the ownership data. However, with the flat file we can only load one period at a time. Is there a mechanism that will enable loading multiple periods at once?

Content (please ensure you mask any confidential information):

We often change the entity hierarchy (we have four hierarchies) to reflect re-organizations and/or reporting requirements. This includes adding new intermediary parent entities or moving a base entity from one parent to another parent. When making these changes, we need to load ownership data which reflects the current structures. We have five years of historical data in the application and building. Is there a more efficient manner of managing the ownership instead of month by month.