If you go onto setting and the onto Do not disturb, you can scroll down and select what groups of people you allow calls from. You can also select the setting right at the bottom where if someone calls you twice within three minutes the call will go though. When you phone is on silent your phone will only vibrate when someone calls you even if you have them in you select group of people that you allow calls from. I would recommend selecting the people you want to have calls from but not having your phone on silent, that way when someone calls you if they are in your select group of people the call will go though and it will use your ringtone.