They were taken away to concentration camps.
They went without ever being seen again.
After the war, they didn't even try to draw their money out of the foreign banks they'd put it in, or to claim valuable works of art that had been seized.
They didn't contact their relations in the USA or the UK, and they didn't return to their homes in Holland.
They didn't take up their old businesses as traders, engineers or authors. They didn't claim their pensions.
We know nowhere that millions of people could arrive without being noticed.
There were very few trains and ships in working order, and their use was carefully rationed.
Food was in short supply and was rationed.
Palestine was occupied by British forces, who had plenty of cameras, until 1948.
Occams razor says they were dead.
Joe says they weren't.