Address Line 1/2/3 Validation

Hello, I'm currently exploring the possibility of auto-populating the Person Address fields, based off the Postal Code that the user enters. I can see it's possible to populate City/County in this way by using validation within 'Manage Geographies'. However I cannot see this option available for Address Lines 1/2/3, and I can't see that any other customer is doing this.

The seeded attributes for mapping do not include address line 1 and I cannot see a way of adding to this list - I can see that additional attributes, so perhaps this would be feasible if I mapped Address Line 1 to Addition Address Attribute 1 but that may cause separate issues.