BroadcastItem: CustomQuerySet or ModelManager

Broadcast and RadioReport are both soft delete models, i.e., they are marked on deletion but remain in the database.

Broadcast and RadioReport are connected with Many-to-Many relation via BroadcastItem model

when displaying report of an broadcast or vice versa with the django template language, all associations are rendered including those that link to an 'deleted' target entity.

A filter must limit to only relations where the deletion flag of the target entity is None.

Also fulfil in API responses