On the lack of wills issue, it sounds like to me that the Billings assets were put into a trust by the parents with AM named the Administrator at the death of the parents. It would be done for tax purposes. Someone said somewhere that she had been given the entire estate because she was the oldest, but Michael is the oldest. But she was in their favor and the one they probably would have selected to administer the estate.
It was mentioned by the family early on that there was a trust for the children.
You can bet that if there were no wills or trust that the courts would be dividing up the assets in accordance with state law. But the court made a quick decision that AM would administer the estate. The trust named her as administrator and the court just agreed. No confusion or discussion because the family knew about the trust and the legal document was in place to make it happen. So, all that happened when the Billings couple died was that the administration of the trust moved from BB and/or MB to Ashley.
Perhaps the items in MB's will were things she owned outside of the trust and the will was more like instructions to the family than a legal document.
Anyway, that’s my guess.