nable selection of the waive option only, while restricting any changes across plans or plan options

For a Qualifying Life Event, the employee should be allowed to move from their current enrollment (e.g., HDHP Employee + Spouse) to the waive option. However, they should not be permitted to change to a different medical plan or switch to another coverage option within the same plan.

Could you please confirm if this can be achieved through configuration? Or else is it only possible through FF? If so can anyone please share a sample FF.