Hi yekepa,
It is the brother , Patrick , who won the DFC, not Peter Christopher. Patrick appears to have been born in 1918. Perhaps he was a half brother or maybe Hugh and Gladys were together before the divorce in 1925. It won't be possible to find out anything on Peter Christopher's service as records are still with MOD, although you can apply if you meet certain criteria.
We have included information on the other family members as you did ask about parents and siblings in your first post.
Edit : By Patrick I mean Patrick Joseph Thomas , not Michael Patrick H.