Can you set up that other person as administrator, in addition to yourself? The interactor licence, which that user apparently already has, allows it.
Administrator option gives that person way more privileges than needed. I will have to rule out System Admin as well as Content Admin options here. Moreover, we need to open scheduling option to not just one person but to handful of people per project, I am sure you would agree that Admin rights cannot be open to wider end-user community.
I wonder if "Project Lead" role can do the trick, but there is no documentaion on "Project Lead" role.
Entirely agree on the dangers of willy-nilly giving out admin rights.
I looked up Project Leader in Server help and looks like it gives admin rights to workbooks in the project only. No specifics on schedule.
The Project Leader role allows a user or group administrative access to all of the workbooks contained in the project, including the ability to specify project permissions.