Question about using a coat of arms

[SD+G Grandson]

Hello
I am the grandson of a SD+G solider who served with the highlanders from 1940-1945 my grandfather's name was Allan. T. Pekeski unfortunatley he passed away last year in August, what my question is, I was thinking about using the SDG cap badge coat of arms and putting it on the back of jacket with my garndfather's name, the reason I ask is because I know relatives can't wear the medals of loved ones the served in the first and second world war. I just need to know if I can use the logo so I can honour my grandfather's memory. If anyone has any information it wold be appreciated.

Thanks again

"Gone but not forgotten" RIP