Relationships between new and existing object Realm react-native

I would like to create a realtionship between a newly created object (lets say Identity) and a already existing object (let’s say City), also many identites should have a link to one City. I’ve tried on-to realationships, to-many realtionships and even inverse relationships but nothing seems to work. Every time I get the same error that I am trying to create an object with the same primary key.

Identity object is:

    insertIdentity = [{
      name: 'Identity',
        city: City,

Where both identity and city have primary keys.

Is what I need possible with realm?

@Milan_Nikolic You can create a many-to-many relationship with Realm - is that what you are wanting to do? You should be able to create a List in Identity for City and a List in City for Identity

Does this work for you?