Margaret Merigan : Short Biography

I have very little info about Margaret's Irish origins.  Any help to locate info is very much is appreciated!  Margaret immigrated by herself to the USA on a ship from Liverpool, that arrived in New York City in June 1849.  She married, raised a family in Leaf River, Illinois & died in 1922 in St Louis, Missouri, USA.  On the US Census of 1900 she listed her birth in Dec 1831.  I have no other reliable source data on Margaret's birth.  Family lore says she was from County Longford and I found a Cashel Parish record for a Margaret Merigan, baptized on 14 January 1833 in Loughane, with parents Edward Merigan & Mary Kennedy, and sponsors Ioanni & Maria Kennedy. This baptism record might indicate a birth in 1832 (rather than Dec 1831).

Although Margaret shows her last name as Merigan on the immigration ship (in 1849) & on her later marriage certificate (to James Powers, in 1858), her daughter listed her maiden name as Finn on her death certificate (in 1922). Also listed on her death certificate, are Margaret’s parents, shown as John Finn & Elizabeth Greffin.  Her obituary, in the local newspaper, says that Margaret was the “dear sister” of James Finn (still living at that time).  I have been unable to find information on a James Finn, that I can correlate with Margaret.

Questions (for discussion purposes):

1.  Are there any Merigan families, currently living, who might have information that an ancestor named Margaret Merigan left for the USA in 1849, when she was very young?  (I’m looking for evidence - even family stories - that might show I have located the correct Margaret Merigan, who emigrated from Ireland in 1849, when she was about 16 years old.

2.  Are there any Finn (or Flynn) families, that were known to be close to the Edward & Mary Merigan family in ~1849, and who had a son named James Finn, who also immigrated to the USA?  (He could have immigrated separately, but James & Margaret made contact in the USA, and the contact was frequent & close enough that Margaret’s daughter thought that James was a sibling, rather than close family friend from Ireland.)  It is also possible that Margaret’s daughter mistook Margaret’s last name to be Finn, and called her actual “sibling” James by that same last name (Finn).   Is there any family evidence of her brother James Merigan also immigrating to the USA around 1850?

3.  Does anyone currently living, know was the family circumstances were at that time, in 1849?  It must have been very hard way back then, knowing that you might never see any of your family members again.  I’d like to know if the family that remained in Ireland continued on to survive those difficult years?