I have something similar set up to silence my phone at night (i.e. during certain hours of the day). I have all sounds silenced except under "ACTIONS" I have "RING LOUD FOR IMPORTANT PEOPLE" and have certain family numbers listed. If any of them calls during the night it rings at full volume (adjustable)..
I use SemiSilent. You choose what numbers you want to whitelist and only those numbers will ring when ringer is off. I use this at bedtime so I'll only be woken by family in case of emergency.