I agree that Arthur's death would have pushed Molly a bit over the edge. She had already lost her twin brothers in the first war and if her husband was killed early on in the second war she would have pulled all her children back closer to her. In my opinion Molly is a force to be reckoned with and she would have let anyone, Bill or Charlie, talk her out of protecting Ron and Ginny and even to some extent Fred and George from participating in the efforts to take down Voldemort. Without Ron the whole dynamics of Harry and Hermione would lead to a different ending.

Steph//Puff