In many countries, it's very common to war veterans fly flags related to the war he participated. I've never saw something similar in Brazil, but I estimate hundreds or thousands of soldiers of WW2 are still alive. What I'll comprehend on this post, however, is a flag to be used by the families of all the soldiers that fought on the war, including those that died on battle.
All the Brazilian soldiers in WW2 where organized under the FEB (Brazilian Expeditionary Force). Its patch was formed by a snake with a pipe on the mouth, in reference to a flag (sometimes attributed to Hitler) that "it is more likely a snake to smoke than Brazil to go to war":
This badge is sometimes used, on a white field, on flags of veteran societies. I suggest something along those lines:
The smoking snake gains a treatment that resembles very much the original patches. This design could be distributed by the veterans societies or the Armed Forces, for example.
Your comments are welcome. Feel free to comment.
It's only a creativity exercise, no non-vexillological statement intended.