You can easily create and link a new organization to your existing login as follows:
Sign into your Xchart account.
In the upper right menu, select "switch organizations":
Then click "create a new organization":
Follow the steps to set up your own practice as an organization.
You can use the same login to join as many organizations as you want
You can also be invited to join an established organization and link it to your same login even if the invitation wasn't sent to the email you use to sign in to Xchart.