Where did they get their money to live? That’s the question which begs an answer.
Plenty of possibilities, will require actual journalists to pull the property records of the address once the situation calms down a bit. FOIA on SS numbers, SDI, FICA , welfare benefits, college loans etc.
But in general, Two teens can live pretty cheap.
IF the parents got up and left, there is still possibility they defaulted on the mortgage, but haven’t been foreclosed. Terrorist sons could be living rent free.
Add in welfare and some off the book work or petty drug dealing and living in Watertown, ...
again, all speculation, but living in Watertown is not an expensive proposition.
Al Qaeda scholarship?