I have made a customer attribute as 'sales_executive' and it is displayed in add new customer form in admin. It is also displayed in customer grid by adding a add column and but now I want to display the same column in sales order grid also. So What I want to ask is Do I need to make another 'sales' attribute for it. Or How to do it?

Add New Customer Form. Added dropdown attribute as 'Sales Executive'

Customer Grid where a column is added as 'Sales Executive' and Id is also displayed.

Sales Order Grid. I have added a column as same 'Sales Executive' but unable to get Collection of this customer attribute.

How to obtain collection in Sales Order grid? Any logic change? Or what to write in _prepareCollection() ?