How add new values in subform multiselect/checkbox ?

How add new values in subform multiselect/checkbox ?

Hello! I have easy question, how i can add new values in subform multiselect or checkbox.

I'm created script, but he doesn't working.

  1. values = {"option","option 2", "option 4"};
  2. subform.checkbox:ui.add(values);

And i tried this
  1. values = List:String(); 
  2. values.addAll({"option","option 2", "option 4"});
  3. subform.checkbox:ui.add(values);
And i tried this 
  1. values = List:String(); 
  2. values.addAll({"option","option 2", "option 4"});
  3. for each val in values
  4. {
  5. subform.checkbox:ui.add(val);
  6. }

What i do wrong? 

I want to add new values after load form. -  http://prntscr.com/hdsdi8
Can i add new values in multiselect or checkbox on use function onload ? or can there be another solution?