Of course this isn't really a story about Doug it's really a story about me where I do need to allow my aging father to call me at any time of the day or night. But I don't really want to get any other calls at night so I have do not disturb set on my phone from my bed time to when I wake up. I'm embarrassed to tell you what time my bedtime is so I won't but in any case if I want my father to be able to ring through.
There's a simple trick I can just go to his contact entry in my contacts, go to the ring tone option, and under a ring tone there's an option to allow emergency bypass. Then that contact will be allowed to ring through no matter what time of the day or night.
You can do the same thing under settings where you can select various groups that are allowed to ring through. For example I also have all of my favorites allowed to ring through so anyone who's on my Favorites list can call me at any time and finally there's an option that allows people that if they call you twice in quick succession it won't ring the first time when you have do not disturb turned on but it will ring the second time. That way you can tell people if you need to reach me after hours call me twice in a row this gives you a lot of flexibility and do not disturb so you should check these features out on your iPhone.