Using Grav in an existant Symfony project

We are interesting by using Grav CMS, to add CMS feature to our existant Symfony3 website.
Why ? We would like to add articles/news to the current site by using an admin interface, with a text editor and an easy interface to create/manage tree, multi-language news etc…
The specific of our site will must stay in our current Symfony.
The idea is to add Grav and use it only on specific route for specific page we will add in the future.

How can we handle that ? Do we need to create Grav project and merge the current Symfony we have in it ? Or the reverse way ? If yes, how ? Or any other idea ?

Thank you for your help !