In BulkImport V1, when you upload student file, along with parents data, if the csv parent name matches along with phone number, it will update parent's profile and add that email address to the matching parent. If the names don't match, it will create a new account with that email.

For example, 
There is a student Emily Smith, with parent Robert Smith, who is already having bloomz account created with  phone 18231234567, and we want to add email address to that account.

Existing Student data

Existing Parent Data

The bulkimport data should have the student row, with the matching student sis_id and parent phone field should match the phone number to the existing account, as well as parent's name should match with the parent, we are updating. 

For above case, it will update Robert Smith's account with the email provided,

If the parent's name will not match with the existing parent with the phone number, it will create new account

For above case, it will create new account for Enna Smith with the email id, as  shown here