Reference to parent node on entity form type
Prepopulate works by lifting values from the request url and inserting them into the rendered form. If it is not in $_GET it will not appear. Using views with a menu tab will mean that you will have to add parameters to the url whether you use Prepopulate or not. I think you should back up and reconsider your approach.

I would suggest exposing the form as a block right on the pages you want. That way the page is easier to identify. If you use Bean it is a simple matter to create a block for your Entity Form Type.


Enable the Bean and Bean UI modules.
Go to /admin/structure/block-types and click 'Add new block type'.
Give the block type a name (eg Entity Form Type Block).
Under 'Manage fields' add an 'Entity reference' field. Select box widget is fine.
Under 'Manage display' select 'Rendered entity' and 'Render as full content'.
Go to /admin/content/blocks and click 'Add new block'.
Give the block a Label (eg. Request more information block) and a title.
Select your form from the dropdown, and save.
Go to /admin/structure/views/add and create a view called 'Node List' showing 'content' of type 'all'. Uncheck the 'Page' display. You are creating the master only. Click 'Save and Continue'.
In the view edit screen, Add a display -> references.
Configure the 'Title' field and uncheck everything (no label, no link).
Under 'Advanced' configure a contextual filter in Content:NID. Check 'Provide default value' and select 'Content ID from URL'. Save your view.
Go to /admin/structure/entityform_types and click 'Manage fields' for your entity form. Edit the nodereference field and set it to required, number of values = 1, and at te bottom under 'Views - Nodes that can be referenced' select your 'Node list - references' view.
Go to /admin/structure/block and set your block to display on the nodes you want, and for the roles you want. It is important to note that the block permissions will override any access permissions you have set on the form.


The entity form will now display on the selected pages, and the user will be required to select the node reference to submit the form. The list presented will be limited to the current page.