How to add a backslash to URLs in Wix?

I have a restaurant page, www.ghoomarthali .in, and I need to have many pages under a promotions category.
for example:
www.ghoomarthali .in/promotions/ghoomar-chhat/
www.ghoomarthali .in/promotions/navratri/
www.ghoomarthali .in/promotions/new-year/
and many more…

But I am not able to create a custom URL with backslash in it, it gives an error message, “Enter a valid URL. You can use letters, numbers, or dashes.”
It only allows URLs like:
www.ghoomarthali .in/ghoomar-chhat/
www.ghoomarthali .in/new-year/
www.ghoomarthali .in/navratri/
www.ghoomarthali .in/promotions/

How do I create the nested URLs?

Where is it that you trying to create the URLs?

Through the SEO Basics settings in the Page Settings, see screenshot

@nirakht Ah, sorry, I thought you were trying to do this with code (Velo). I would recommend contacting Wix Customer Care , as they will be better able to assist with your issue.

It is NOT possible to have 2 layers. You need to use wix router (coding) in order to achieve this goal.