Verify Gray Family

John Gray and Jane Hughes of Kirkaldy, Fife had 2 sons Andrew,born 1882 in Edinburgh and Angus born 1884, Kinghorn. They were reportedly killed in France serving with the Black Watch regiment on 09/05/1915. Andrew, Lieut. and Angus Pvte. This differs from my mothers report who thought they emigrated to the USA.
Andrew Gray's casualty details list his age as 38 which would be 5 years different to birth record.His wife Mary Kerr Gray lived at 10 Wellington st. Edinburgh. How may I get details to verify this happening. Their younger brother John Gray born 16/4/1886 in Kirkaldy, lived in Coatbridge, near Glasgow at some time. I can find no record of this person or his family. Any help , most appreciated.