If the Courier kills his wife or daughter, he will not talk to them and say "I should kill you right here, for what you've done" when interacted with. This makes it impossible to complete Aba Daba Honeymoon. But a way to fix this is, go to him when he is sleeping and punch him he will wake up and say "Hey what was that for?" then a chat option should appear.
At night, Don won't be found at the Crimson Caravan camp. He can instead be found at his home down the road from the camp.
On rare occasions, Don may be killed during his commute between work and home, as his neighborhood is considered part of the Wasteland, and Fiends may randomly spawn in the area around it (especially during the night). This only occurs if the Courier is in the same active map cell as Don while he is traveling between locations.
E-Mails from his Average locked terminal in the main offices suggests that Don Hostetler is having an affair with his secretary. In computer messages she describes having a "wonderful time last night," and she is apparently scouring the markets for pre-War lingerie.