Reply is related to Statement. Estimate is a type of Statement. Estimate is a synonym of Guess. Guess is related to Answer. 
Invite is related to Invitation. Invitation is related to Wedding. 
Reply <--RelatedTo--> Statement <--IsA-- Estimate <--Synonym--> Guess <--RelatedTo--> Answer 
Invite <--RelatedTo--> Invitation <--RelatedTo--> Wedding 