Database design for students and families/parents
How about creating a separate Table called Person ? You will need separate tables for storing Guardian or Student related information and they both can refer to person Id.

Instead of family you can have relation table that joins two different Person with Extra column of RelationshipType (and of course another lookup table.)

Address table can connect to person table as well and same as Address you can have another table for contact details as well with contact type lookup table that stores values like phone number, email, mobile, work email, work phone etc.

This will also help you in scenarios where an ex student becomes a guardian.

Hope that helps.

Maulin Thaker