There are several possibilities listed in the London Gazette, but none seems to have the exact three names, as is quite normal. - usually only one forename is given and there a number of Charleses. The Gazette published citations for these awards which were awarded for gallant actions, just below the level of a VC.
If you look at the Great War Forum and post there, they have a contributor who seems to have a list of DCM winners and may be able to help [Apologies to anyone on THIS Forum who has the same source!]
Another source is the Medal Index Cards available via Ancestry or the National Archives online. Anc.. have the cards for campaign medals, but I think you have to look in the NA for DCMs, as they are usually on separate cards.
Worth pursuing!
A