Is it possible to add multiple site collection administrators assigned in the Nintex Workflow Office 365 Create Site Collection action?
If not, is there a way to add a site collection administrator to a Site Collection in Nintex Workflow?
Afaik this is not possible via Office 365 Create Site Collection action. However, you should be able to do this via REST by updating the "isSiteAdmin" property of the user. This can help to get you started: office365 - How to set sitecollection administrator to user in SharePoint online using rest api - Stack Overflow
Retrieving data ...