I chanced across your post and (this is a long shot) wondered if you might have got any further in your research, and if you may have found a Kelly brother or son called William.  William Kelly was born near Brookeborough (Aghaveagh?), Co Fermanagh around 1808, parents unknown to me.  He joined the Army, married a girl in Dublin, and was sent to South Africa  where he remained for the rest of his 72 years.  I am his direct descendant, and am seeking his N Ireland beginnings.  
Any morsels will be gratefully accepted.