Redirect customer to other website when click buy now (Nopcommerce 2.40)

I have two websites both based on nopCommerce 2.40, one is main website with payment gateway integration done and other just to attract traffic. To my surprise my secondary website gets more traffic than the primary (one with payment gateway).

Now what I want is to redirect my customer to the primary website on the same product which he/she wanted to buy. I have already seen this thing happening in our own nopcommerce.com, when i person wants to buy a paid theme he is directed to other website (Here is the example: https://www.nopcommerce.com/p/999/nop-electronics-theme-nop-templates.aspx)

I want this exact thing. Can anybody tell me how can i do this or what changes I need to incorporate to achieve this?

Thanks in advance.

Is there nobody to help me out in this community? 6 days and not even single reply that to in response of what already has been achieved by nopcommerce Team on this website itself. This is strange.

Guys, I need your help. Please respond.

I also want to do the same.