Adding additional fields to your Offline Message form with Contact Form Ready.
You can use Contact Forms Ready to add additional fields to the offline message form.
Install Contact Forms Ready from the WordPress Repository by navigating to Plugins → Add New. Type Contact Form Ready into the search box. Then click the Install Now button for the Contact Form plugin by Nick Duncan.
Once the plugin is installed the button will turn blue and say Activate. Activate the plugin by clicking on this button.
On the next panel, you’ll be asked to complete a one-question survey asking how you found Contact Form Ready. Answer as you choose or skip the survey. After you submit or skip the survey, you’ll be taken to the Contact Forms panel.
Click the Create a form now button.
Create a form containing the fields you want shown on your Offline Messages form for WP Live Chat Support. For detailed instructions see Contact Form Ready documentation.
Once you’ve finished with your form, click the Publish button.
Navigate to Live Chat → Settings → Offline Messages.
Select your form’s title from the drop-down box to the right of Custom fields.
Scroll down and click the Save Settings button.