Fallout 3 vampire family?

So I finally bought Fallout 3 after so many years. I'm on the mission where you have to talk to the Family, the group of people who drink blood, and I've come onto a slight problem. I accidentally killed Robert, their sentry near the entrance to the lair, and now they all want to kill me. Is there any way to get them to stop fighting me without actually killing them all? Because I'd rather not have 4 people attacking me at one time.