Since Mendix doesn’t currently allow creating user roles directly through the UI, and having hundreds users role will effect the application, a good workaround is to manage access through a custom table. For example, you can create a table called AccessManagement that’s associated to the Account entity. Inside this table, you’d add boolean attributes that define what content each user can see, like ViewFirstContent or ViewSecondContent.
Let’s say you have a user role called Employee, and under it you create two accounts: Employee 1 and Employee 2. If you want Employee 1 to see only the first type of content, you’d set ViewFirstContent = true and leave ViewSecondContent = false. If you want them to see both, you’d set both booleans to true.
On the pages itself, you simply control the visibility of the content based on these boolean values. This way, even though both users share the same role, their actual content access can still be tailored individually.
Not out of the box, but you could take a look at the mendix SDK:
https://docs.mendix.com/apidocs-mxsdk/mxsdk/
There you should be able to create a script, to handle these actions automatically.