Do you employ any at your company? How do you track them to ensure they're given the correct retirement plan?
From my days in the 401k/exec benefit arena --> Generally HCEs are eligible for all plans that NHCEs are but might have limited benefits that are then possibly made up for in non-qualified plans. Such as supplemental health insurance (more at the very top exec level than just strictly being classified as an HCE) or non-qual deferral plans. There is no legal requirement that an employer give HCEs any such plans though.
Much of the tracking was done through payroll deduction elections at open enrollment and throughout the year through payroll feeds to HR and the third party administrators/recordkeepers of the plans. And often one (or more) HR employees are responsible for that specific group of employees.
Our small company has 1. We don't have retirement plans at all.