Is there a way to get a list of all the current logged in users?
On FM Server?
Not without using shell command to query command line tool to output it.
e.g. like this
MBS Blog - Tip of the day: Query connected clients on FileMaker Server by script
Toggle on the Access Log on your FileMaker Server, It does exactly what you need!
MBS and BaseElements plugins both provide ability to do this.
Retrieving data ...