Well, I don't know who these friends are. I have been dying to talk to some of them about this very thing. I can't seem to find hide nor hair of them. So if have an in with them, please invite them here and let's hear what they have to say.
If what you say is correct, you have nailed the motive. It would not be about money at all if depression is in the mix. It would be about a woman whose emotions were out of control, who lost it suddenly and killed at least one child and then scurried around trying to come up with a way out of it. That sort of eliminates premeditation, doesn't it?