How to add new effective dated row Canadian Designated Group information in Person Extra Information

Summary:

When using spreadsheet loader to add new effective dated rows to Additional Person Info the existing rows do not have their end date updated resulting in overlapping records. How do I fix this?

Content (required):

I have been able to create a spreadsheet loader that adds an initial effective dated record to the Canada fields in Person Extra information tables. However if I load additional records with a new effective date for the same employee the existing records do not have their end date updated. I have added the end date to the spreadsheet loader and tried to update that way but get a duplicate error.