HELP NEEDED with matching fields

In the table Security Center
The field Related Employee FN is a Formula Numeric Field  set it equal to the Related Employee

Now use Related Employee FN as the Reference Field in the Relationship between the Site Users and Security Center

When a record is created in the Security Center, it will be related to the Site Users record that matches the Related Employee in the Issue.

Now you can build reports in the Site Users Table for all the Security Issues related to them.