Pre-selection states and pre-requisite choices

I'm trying to create a selection which has a pre-requisite state that must be selected, before you can select additional checks within that check.

So unless a user selects an 'Enhanced Check' they cannot select the child or adult options.

If they select an 'Enhanced Check' then they can select 'Adult' or 'Child' or both.

This selection has an importance factor/weighting to it, hence the colour scheme, but that is affecting the disabled/on/off states of the check buttons. Here's what I have so far:

Could this control be improved to make the choices more obvious and ensure the user experience isn't confused? At this moment in time it's not working for me.