Worker is related to Person. Employee is a type of Person. 
Relative is related to Grandfather. Grandfather is related to Family. Grandmother is part of Family. Grandmother is a type of Grandparent. 
Worker <--RelatedTo--> Person <--IsA-- Employee 
Relative <--RelatedTo--> Grandfather <--RelatedTo--> Family <--PartOf-- Grandmother --IsA--> Grandparent 