Organization admins with the study-admin permission are able to add and remove sessions for each member from the Greek Chapter mobile app (this isn't supported on the web app at the moment).
To add hours to a member:
Open the mobile app
Navigate to the Study tab
Tap the history button in the top left
Change the top toggle to Organization Hours
Each member has an Add Minutes button where hours can be manually entered
To remove sessions from a member:
Open the mobile app
Navigate to the Study tab
Tap the history button in the top left
Change the top toggle to Organization Hours
Tap View History on a member
Tap Delete Session on any study session to remove it. It may take a few minutes for the changes to be reflected across all of Greek Chapter