Helen: Yes I hear/understand what you are saying - don't forget to factor in the memory of the source, the penmanship of the transcriber, or perhaps a simple mis-statement ie. said Mary but really ment to say Jane - but here's another twist many times if a child died young (a few days to maybe several years old) and the parents had another child of the same sex the second child would be named after the deceased sibling ... not a common thing yet it was done by many grieving the loss of the dead child.
Are you sure your Feeney and Lynch connections were from Roscommon ? The reason I ask is that Feeney is fairly common surname in parts of Galway & Sligo, and/or basically throughout the Northwest corner of Ireland but Lynch is 100% a Galway name ... no that doesn't mean they couldn't be elsewhere but in the mid 1800s beening more than 20 miles from where you were born was indeed far far away !! Where did these folks marry? I'd like to know a bit more about them if you wouldn't mind sharing the info.