Disallow new dependent designations while allowing a change in option

Summary:

The requirement is that a dependent not be able to be designated on a certain life event, but the employee may switch options during that life event.

Content (please ensure you mask any confidential information):

We originally had the Change Dependent Coverage Rule set to 'Can remove dependents' but that prevented the employee from designating their existing dependents to a new option. 

Example: Employee is enrolled in Employee + Family with a spouse and 2 children. They have 3 eligible children. The spouse gains other coverage and is getting removed from the benefit enrollment. The employee needs to switch to Employee + Children option. With the Change Dependent Coverage Rule set to 'Can remove dependents' it didn't allow the children (who were already covered) to be designated in the new option. We updated the Change Dependent Coverage Rule set to 'Can either add or remove dependents' to allow the designation of the existing children but then it also allows the designation of