Stopping do not disturb bypass

I put my phone on do not disturb mode at night. I need certain people to be able to reach me in case of emergency, but there are others who are not on that list but will call me multiple times in the middle of the night in order to bypass the do not disturb feature in non-emergency situations. How can I turn off the multiple call bypass on do not disturb mode?

Using an iPhone 6s Plus with iOS 12.2