One more suggestion:
Using an activity log to verify that no one has been using our account.
An idea of what I mean: as having the pages of the banks in their banking online, or Gmail, which tells you the IP address and date of the last connection.
That would be nice to make sure that we who come from our account.
It could also be interesting that the administrator could take control from the other accounts, that is, through an option that will display a list with information about the connections of their users of the system.
For now, that's all that I can think of. I will think of something else.
Best regards and many thanks for your great software. It is very useful.