I understand there is currently no API or Powershell way to register external users before using the Add-SPOUser cmdlet to add them to a group. This means that I have a very manual step in a business process. We are looking to use SharePoint Online to securely share content with external business partners. So I have a business process that needs to validate who has access to what content. We are using DocAve Governance Automation as well as K2 business process workflow tooling, both of which utilize the SharePoint Online APIs, but there is no way for them or with the SharePoint Online Management Shell to add a new external user. Ideally, I'd like to have one of those tools (or my powershell execution from one of them) to automatically implement new external users after they have run through the approval business process. But right now, it's going to be a manual step.