Developing a role based complex user structure for our moodle

Our clients are German based home care institutions (e.g. nursing homes). We want to offer them an additional service - online training for their nurses through our newly installed moodle. (We are still quite moodle beginners.) We would provide the course content. Every home care institution shall have a kind of a super user (but not an admin for the whole moodle administration) that shall be allowed to register nurses on our moodle, grant them access to our moodle courses and receive moodle reportings (e.g. by gradebook). Privacy is key! So these super users shall not see what other home care institutions are listed on our moodle altough they shall make use of the same provided courses probably even with granted access at different times as to the comfort of each home care institution. We need a kind of organigram to succeed with the required structure. Who can solve this task profoundly for / with us? Please note we require the freelancer to proof his / her moodle expert knowledge through e.g. references or other finished projects.