you could do it this way, but that causes lots of data duplication which is what databases are used to prevent.
plus, what happens if you run into a case where you want to relate to three people? you need to add more columns.
This is why you use the linking table.
With the linking table, you link as many clients as you like to as many users as you like
the onBlur event is an html event. it refers to removing focus from one form element and focusing another
Go to the Bindings panel and select your text box. Then click the plus button in the bindings panel and select WA Validation Toolkit -> Client Validations -> required / Not Blank. When you apply this, make sure to set the event in the bindings panel to the onBlur event.
next apply the show hide form element validation response, also to the onBlur event of the checkbox.