You’ll need to insert the values both into the actual data and into the column’s list of valid choices. The latter part requires a more sophisticated formula, but I just happen to have one lying around in the RUC. 
Take a look at the ‘WidgetOptions.add_choice()’ function in here. This function takes a ‘colrec’ as an argument, you can obtain such a ‘column record’ by using ‘Column.get()’ from here.
That should do the trick. Let us know how it goes!