How to select item in choice field by index?

2

Hello all,

How is it possible to select a choice field item by index?

The choice field(A) has a placeholder ("empty" in attached image) and a dynamically read value. And on value change in another choice field(B), this value is being added to the choice list(A), but I also need to have this new dynamic value selected as right now it is just queued under the placeholder.

Is there a way to do this through webcon standard or programmatically?

Thanks in advance :)