Ambos - mas que dos?

Ambos - mas que dos?
 

Is it correct grammar use in Spanish to say "desgraciadamente ya murieron ambos tres" instead of "desgraciadamente ya murieron todos los tres"? In English "both" always means "two, of two". "both men died" means there were 2 men, and the 2 men died. If there are more than two, we must say "all". "All three died" "All four died". Both can never apply to more than two.

No, it's not correct to use ambos tres in your sample. You should use los tres. This implies all of them. If all have died, you could also say todos. If only 3 out of 5 died, though, you would say the number that died - tres. You could include de ellos, in the latter case, just to emphasize that not all had died.

You can use`al menos tres.