I think I figured out what happened. Thanks @dainerra for helping me piece together the most likely scenario.
It is fixable, but I'm going to have to start with my hubby. I think he broke Dawn off Cheyenne in the wrong way at the wrong time, thus setting off Rascal and Fiona. I think Dawn was enforcing her dominance over Cheyenne, sensing she was reaching the fertile stage of heat and my hubby thought it was a fight, grabbed Dawn and publicly disciplined her. This unstabilized Dawn's role as alpha, and caused the fight my husband told me of.
So I'm going to rehab Dawn and make my hubby participate, as well as teach him how to understand pack behavior and language. This whole thing could have been prevented if I had been more pushy with my hubby learning this from the start. I don't argue when he tells me my car needs work (he is a mechanic), now he is going to do the same for me when I tell him how to handle the dogs.
My kids are going to help too. I have taught them some basic dog body language since they were tiny. The can tell an aggressive dog, a fearful dog, and a happy dog. We are working on more subtle signs, but they have ears, tail, and bristling down great. They can help my hubby understand these signs. I haven't taught the kids how to handle fearful or aggressive, simply taught them how to see that and stay away from those dogs. But the kids are further along with dog skills than hubby, so they can help teach.