Enroll Plans on specific condition

Is there a way to add error or warning messages to the Benefits Enrollment component based on certain criteria? For example, if an employee is not currently enrolled in Choice Plan HRA we do not want them to be able to select Choice Plan HRA during benefit enrollment. We would like to provide an error message requiring the employee to select another plan as they are not eligible for Choice Plan HRA.

Or Is it possible to show Cholce HRA plan to only who already have it and other should not show that plan at all?

Your response is much appreciated.