Western is a type of Sandwich. Western is related to Democracy. you are likely to find Union in/at/on Democracy. Union is a synonym of Coalition. 
Partner is related to Opponent. Opponent is the opposite of Advocate. Supporter is a type of Advocate. Supporter is a synonym of Champion. 
Sandwich <--IsA-- Western <--RelatedTo--> Democracy <--AtLocation-- Union <--Synonym--> Coalition 
Partner <--RelatedTo--> Opponent <--Antonym--> Advocate <--IsA-- Supporter <--Synonym--> Champion 