I know how to grant permissions to groups via workflow, but is there a way to add and remove people from those permissions groups via workflow? For example, if the user entered the users who should be in the group via peoplepicker, then the workflow would place those users into the appropriate permissions group. Is this a possibility?
You can install the custom workflow action solution from this link. However, if you have third-party workflow tool like Nintex, you can easily find this action.
The Solutions includes the following SharePoint Designer Workflow Actions:
Create Site Action
Create Group Action
Add Users to Group Action
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