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oops...after some research I found:

This will do the trick for me for now. Setting access rights trough JavaScript depending on the Login and/or UserName.

"Access rights to users" is exactly what I'm missing for now.

I understand it takes a lot of development capacity/time, but after 2 years...

A short term solution could be to implement a system token with current login/username or -HWID. Based on that information we can control the visibility of items. As a kind of access rights.