Sample to disable enable TextBoxes in a StackPanel and set default width of TextBoxes for specificly tagged TextBoxes, in this case the 12 under "Number of Covered workers"..
WPF: get all controls of a specific type using C#
In this article language extension methods are presented to locate controls in containers such as a windows Jump , grid Jump or StackPanel Jump for performing business logic like obtaining a selection from a group of Checkboxes, a selected RadioButton in a group or enabling/disabling specific types of controls.