1.  Create a new import file in CSV format ensuring it contains the spouse name, constituent type, spouse address and the lookup id of the existing spouse in ResearchPoint.
2. Create a new Import processs using the Constituent Update Batch template.  You need to ensure the Constituent Update Batch template has fields for Constituent Type, Address, and Spouse Lookup ID.  
3.  Map all fields for the new spouse to the main constituent fields in the template.  
4.  Map the field for Spouse Lookup ID to the existing spouses lookup id in the file.
5.  Continue with the import as normal.