Hi Brian, I have looked for a Kelly/Hargreaves connection, a Blennerhasset/Hargreaves and a Kitchener/Hargreaves connection and after a quick search I have come up empty handed.
The reason I did this is I remember doing a search some time ago and the person took their mother's maiden name as their new name. However given the fact that many Irish people of that time would have been reared by their grandparents it could be a grandmother's maiden name.
The Blennerhasset family tree is fairly well documented here
http://www.blennerhassettfamilytree.com/
and here
http://humphrysfamilytree.com/Blennerhassett/
but you probably know that already.
I can see 2 possible avenues of research for you
1. Check with Kew Gardens military record for a Tralee man of that time period who served in the army. (long and tedious I know)
2. Via Autosomal DNA testing see if any of those names show up in your matches. Depending on your own birth date, you may come up with some useful matches. You may have already done this but if not then upload your Autosomal DNA results to gedmatch.com and join the Kerry DNA Project Group on Facebook where we are trying to untangle our trees.
Congrats on doing the 'big Y' test. And good luck if you try the Autosomal DNA route. A strong second cousin match could lead you home.
Warm wishes
Martine Brennan