Dear Marybethe
Welcome to Ireland Reaching Out and apologies for the long delay in getting back to you.
I had a look on rootsireland.ie and located a marriage record for a Peter 'Minan' and Catherine Daly on 23rd Oct 1848. The parish is simply listed as 'Cavan'. The witnesses are Patrick Car and Sarah Daly, presumably, Sarah is Catherine's sister. Peter is recorded as a soldier. Have you also checked with the National Archives in London for any army information available:
http://www.nationalarchives.gov.uk/help-with-your-research/research-gui…
I couldn't find a baptism record for any children of Peter and Catherine. I also tried for a baptism for Sarah Daly, without any luck (difficult as we don't know her parents' names).
Let me know if you find anything at the Archives, I would be very interested in finding out more. I wouldn't think there is a headstone for Patrick Jr but this would not be unusual as most graves at that time would have been marked by a simply stone marker.
Best wishes
Clare Doyle
Genealogy Support