Advice required on how to set-up allowable dependent checks on a Benefit Option

Summary:

We have a requirement to have a dependent check on family option cover to ensure the employee has to select spouse AND at least 1 child before they submit.

Content (required):

We would like the system to return an error message when an employee tries to select Family Cover on the Private Medical Scheme and does not select spouse AND child. We currently have the following set-up:

This set-up allows the employee to submit if either of the dependents are selected.

How do we switch this to do the check we require.

Any advice would be much appreciated.

Version (include the version you are using, if applicable):