Registered data source

The registered data source is basically a PHP function which returns a list of options for select, checkbox or radio.

You can learn how to register new data sources here https://wpadverts.com/documentation/custom-fields-paid-addon/ in the “Using Registered Data Source” section.

If I update the code, will it be overriten by next update? is your plugin support child theme?

thanks
Felix

Depends on where you put the code, if in wpadverts directory then your code will be overwritten when updating WPAdverts.

Ideally you should create a new plugin and put the code there.