How To Map Custom Field From Opportunity To Opportunity Product Entity

I Created Custom Field Of Type Lookup Called "Customer Name " in The Opportunity Entity and Create another Lookup Field 
Called "Customer name" In Opportunity Product Entity , 
I need To Map Value From The Opportunity Entity To Opportunity Product 
I Try To Do this By Edit 1:N Relationship Of Opportunity Entity With Opportunity Product 
But it Doesn't work
Any Solution For This Case?!