How to dynamically add items from different entities to lists in ASP.NET Core MVC

This is my first experience with lists in general and I have kinda complex scenario. I want to add an object of type Story that has a list of Sentences that can be added dynamically. Sentence has a one-to-one relationship with Image and another one-to-one relationship with Audio (that are optional to add). I managed to add the sentences list to the database along with the story object. But I have no idea where to start with the other two entities.

How to send data from ajax to a base controller method that runs on every visited page

I want user’s latitude and longitude to be updated on every page visited. In order not to duplicate things, I created a base controller where I also implemented the onActionExecuting which allows the method to run every time on every action from the derived controllers, but I can’t figure out how to pass the latitude and longitude parameters since they are only passed from the browser through an Ajax call.