Andrew McDonnell is indeed one of the civilians shot during the Rising. His name is now on a plaque in Glasnevin Cemetery. Mt grandmother, who grew up in Fitzwilliam Lane, never mentioned this when I asked her about the family history. She lived near Peter on Clonard Road also (where my mother also grew up).
Andrew McDonnell's British Army Service record is available to view on FindMyPast.
Hope this helps!
