This action allows you to add a user into a group on the current site.
We aren't checking in the group currently exists, or even if the user currently exists. The Call Web Service action has error handling enabled, so any errors will be caught and put into the Error parameter. See the following UDA's for similar functions:
There's one thing that all these UDA's have in common, and that is, they use a Nintex Workflow Constant named "Admin Credentials". If you want to have a different credential, then feel free to update the UDA's.
Nintex Workflow 2010
SharePoint Server 2010
Once you have these UDA's, you can go to Manage User Defined Actions in Nintex Workflow 2010 and import them in. Make sure you have the "Admin Credentials" constant, otherwise this won't work at all
When you have them imported and published, in the Nintex Workflow designer, you'll see this: