To add new site, enter a unique title/domain (without www.) and select options for googlebot/block javascript (only on (sub)domain). Then, enable your new site in options (cookies will be removed by default).

List of custom sites

Disable deleted sites in options.

Json file

You can edit the text area and save (only when json-text is valid). Clear & save to reset. You can also export/import json-text for new installations.