Greaghglass,
Is read your post a few days ago and for some reason Charles McCabe's name stood out. So I went through the files I have on Thomas Donnelly and his name came up. I only have a few details but here they are.
Thomas Donnelly was a section leader in the F Coy 2nd Battalion and he names Charles McCabe as his Comdt between 1st April 1919 and the 31st March 1920. Charles's address was 29 Ellesmere Avenue, North Circular Road.
The documents I have relate to Donnelly's application for pension and following a meeting with the pension board he was asked to submit more info in writing. He listed various activities and details and one of them is listed as follows.
'Charlie McCabe, Christopher Fitzsimons and myself took part in and got to seize a rifle in the Town Hall, Clontarf, the three of us were armed. I recieved a smith and wesson revolver to go on this from John Ward, that would have been about 1920'.
That's it i'm afraid. Hope it helps
Gavin