Add up to six custom payment and fulfillment statuses to the store. Manage names and availability of order statuses. Read about working with the feature in Control Panel: https://support.ecwid.com/hc/en-us/articles/7837194005020
This endpoint supports GET and PUT requests only because technically all six new statuses are already added to stores in a disabled state.
Currently, there are three custom payment and three custom fulfillment statuses to work with. Default statuses cannot be changed, For custom statuses, you can change their availability, name, translations, and ability to trigger the "Order status changed" email.
If your business/service requires more custom statuses, please contact us and tell us more about it!