how to add custom field in new order product at back office in prestashop 1.6

[NishantVadgama]

hello ,

 

       I want to add custom field when admin place new order in that order product have custom field only when my module is installed as well as enable otherwise it works as it is default, 

 

 

    How can i acheave this i have tried to override AdminOrdersController.php it partialy works but it also call template file (form.tpl) and i dont know how to over ride that template (form.tpl) file and where to place i have tried to place .tpl file to "{root}/override/controllers/admin/templates/orders/form.tpl" but it will not work

 

please help me. i have attech a image what i want to do actually.

[NemoPS]

Have a look at the ajaxProcessSearchProducts method of that controller first, I believe it's the one being called once adding a new product. 

As for the template, what about

adminfolder\themes\default\template\controllers\orders\_new_product ?