added relative knowledge loss function

app/models/concerns/user.rb

@@ -11,6 +11,7 @@ module User
     has_many :user_proxy_exercise_exercises, as: :user
     has_many :user_exercise_interventions, as: :user
     has_many :interventions, through: :user_exercise_interventions
+    accepts_nested_attributes_for :user_proxy_exercise_exercises
 
 
     scope :with_submissions, -> { where('id IN (SELECT user_id FROM submissions)') }