Please stop my madness- re: Hallan, Halloran?

 

   Hi,

for years I've been trying to find ancestors on my dad's side: his mother Augusta, her father-Daniel Hallan, born in Kansas or Ohio, USA. Daniel's father is Patrick.

Patrick interests me, have been for years, he and his wife, and her family as well.

 Patrick was from Ireland, maybe Clare, never came to USA. However, I've run across sites listing O'Halloran or Halloran as the name. I cannot find any Hallan, Hallen, etc., in Ireland. Loads of O'Halloran's and Halloran's. Where can I find the truth,

was Patrick an O' Halloran or Halloran and changed his name to Hallan/Hallen before sailing from Ireland, or  somehow getting to Liverpool to sail from there in 1850(or about then), on the ship Princeton,  

can I find the manifest before he left Ireland to see his given last name, possible papers listing his parents, where they lived, etc., or when he arrived in Liverpool to leave from there and and the same info possibly listed? 

Or if he's an O'Halloran, et al.,what ship, other info?

I very much want to find this info for myself, but mostly for my young grandchildren. I have a few very serious medical issues, so timing is important as I've been searching for years. Hopefully I've searched in the wrong places, and someone here can guide me.

Patrick, in some places, lists him as a Jr., and married Mary Grogan. His birth around 1830, (maybe Clare) with arrival in New York around 1850 on the ship Princeton from Liverpool.

Other places list Patrick Halloran.

My Ancestry info have my ancestors from: Dublin, Cork, Clare, Galway, Limerick, Kerry, Waterford, Tipperary, Donegal.

I know this is like finding a needle in a haystack, and believe me, I'm covered in hay!

If I could find documentation of birhtplace, his parents, grans, etc., would be amazing.

Tess

p.s I've checked: Family Search, My Heritage.