Data Import

Content

We have a Billing Custom Object which is Aggregation relation to the Parent Object , 

The Data is imported to this Billing Object via CSV file , What I'm trying to achieve here is to create a Tab (Which I did for the Billing Object Under the parent) and the tab should display the billing Data related to the Parent ..

Only problem is I don't have the Parent Record Id value in the Data imported in the Billing Object  and want to find the match in the parent to link correct Biiling records  based on say First Name , Last Name , Email and other field .