There is truly much interesting things to investigate regarding sonderkommandos.
Their working time for example as we are told they were killed periodically.
But still some managed to work very long and even in several places.
Here's a little list I gathered:
Filip Müller, Slovak, three years, Auschwitz & Birkenau, Krema I, Krema III, Krema V, evacuated on death march
David Olère, Polish-born French, two years, Bunker 2 and later in Krema III, evacuated on death march
Dario Gabbai, Greek, nine months or eight and a half months, Krema II at Birkenau, evacuated on death march
Jakob Gabbai, Greek, same time and working place with his brother Dario?
Shlomo Venezia, Greek, eight months* or six months** at Birkenau
*His book **Wikipedia
Maurice Venezia (later Morris Venezia), Greek, Birkenau, also 8 or 6 months like his brother Shlomo?
Henryk Mandelbaum, Polish, Birkenau, Krema II? and burning pits, evacuated on death march where he escaped wearing civilian clothes. (Wikipedia)
Henryk (Tauber) Fuchsbrunner aka Henry Fuchs, Polish, about two years, Birkenau, Krematoria II & Krematoria IV, escaped during a death march
Szlama Dragon (Shlomo Dragon), Birkenau, Bunker I or II, escaped during a death march
Abraham Dragon, Birkenau, Bunker I or II, escaped during a death march
So, there was some brothers working together and they survived the ordeal and even the death marches.
Some friends like Tauber and Dragon managed to escape together during the marches.
About that periodical killing of sonderkommandos with some emphasis added:
"They used to change the Sonderkommandos every six months
because we knew how the final solution was done
-Dario Gabbai, 1999http://articles.latimes.com/1999/oct/20/news/cl-24100
"Members of the Sonderkommando who worked in the gas chambers and crematoria
were murdered after a few months
and replaced with others forced to carry out the Nazis evil crimes..."http://www.holocaustresearchproject.org ... hlomo.html
"Most Sonderkommando members were systematically killed by the SS
. But fate allowed
Shlomo Venezia to survive, and the horrific privilege to bear witness
- History Wirehttps://www.amazon.com/Inside-Gas-Chamb ... 0745643841
But still there was these sonderkommandos working much longer than few months and were evacuated with others on so called death marches.
Some had the possibility to even change their working place like Müller from camp to camp. Probably a good worker, even though he tried go into the gas chamber himself.
The always efficient SS was apparently doing very sloppy job by not identifying the crematorium workers, not killing them and even letting them to escape from the marches.