Configurable List Widget: Ability to set unique selections on some fields in the widget.

(1) I want to set only one of the adults entries as Primary Contact. I can add a 'Primary' column dropdown. However, is it possible to create some conditions so that there is no more than one primary?

The Configurable List widget cannot be handled by conditions, this is why you cannot use conditions to set unique selections in the widget. 

I have also tried to add a new column with a drop down and show only the first one, hiding the other  fields, but I cannot find the needed code to do it, basically I wanted to set the first row for the primary contact. 

I could not find a way to do this with the widget, this is why I will escalate this thread to our second level as a feature request, I think that our developers may implement unique questions or selections in the widget. 

Do note that features are considered depending on the amount of users requesting the same, although we cannot provide an ETA about when it will be available, we will let you know via this thread.