Buy is the opposite of Free. Free is a type of Issue. Issue is related to Problem. 
Decorate is a synonym of Grace. Grace is part of Love. Love is related to Relationship. Supplier is a type of Relationship. 
Buy <--Antonym--> Free --IsA--> Issue <--RelatedTo--> Problem 
Decorate <--Synonym--> Grace --PartOf--> Love <--RelatedTo--> Relationship <--IsA-- Supplier 