Eligibility of one plan during retirement is based on the plan enrollment before retirement

There are 2 programs for the employee. One is during the active tenure of the employee in the organization, and the other program is for the retirees.

If employee is enrolled in supplemental employee life plan before the retirement period, the employee should be eligible for supplemental plan for the retiree program(ie: Retirement program). Else the plan should not be available for the employees. How to achieve that. I tried using the eligibility formula, partiipation and rate eligibility and attached it to the retirement supplemental plan type. However, it is not working as expected.