hi Koenvdz,
you can use "Joomla User" to assign joomla user to record,
You can automatically assign user to record as author of record.
and control:
-if someone can see the record
-if someone can edit the record etc
If you want to know more
you should read about joomla ACL:
docs.joomla.org/Access_Control_List
www.google.pl/search?sourceid=chrome-psy...e%3Aj-cook.pro%20acl
btw there are some gimnastics if you want to gain access to records
to the group of users where author is in
and the author is in many gropus