I did some research into the Soden brothers who are commemorated on the Winchcombe memorial in Gloucestershire. One brother flying with 56 squadron was killed flying a Hurricane in 1940 during the Fall of France and was subsequently awarded a posthumous DSO. The citation for which was worthy of a VC. The other brother was killed when the SS Laconia was torpedoed on its way from North Africa. He had survived the Battle of Britain flying Spitfires and North Africa campaign flying Tomahawks. The Third brother served in Burma and died of Blackwater Fever in the jungle.
For the purists. It should not be possible to be awarded a posthumous DSO as you cannot be made a member of the Order if you are not alive at the time of recommendation. George V1 made a special allowance in this case as the next of kin had already been informed on the condition that it should never happen again.
Regards