She was a newly married woman who lost her husband. The lawsuit will throw everything out there and amend as needed to get some sort of settlement. Doesn't Amtrak have a per-person limit as to liability? And, no, they won't likely get anything from BNSF - even if their CEO personally pulled spikes out of the ties and hacked the rails. Amtrak's indemnity clause.
As for the cause of death of the three individuals, there may be a summary in the final NTSB report as there was in the 2005 Glendale Metrolink report. In that report, the cause of death was being crushed against the hard-bolted club table. Table didn't break away, no seatbelts, and tragedy.
In this particular wreck, the railfan who was interviewed several pages ago was in the SSL. Said he survived because he hung onto a table stanchion. Said the windows beneath him were gone and he could see ballast below an open gap between the toppled, moving SSL and the ground.