I believe Francis parents were Francis & Sarah Feltus. Francis (jnr) came to USA in 1854 on ship Webster with his brother Henry ,his wife Margaret,her children from 1st marriage plus more of the family.
In 1870 census Henry & his wife Margaret nee Crowley (formerly Hawkins) had their niece Hannah Stacey with them.
Hannah was the daughter of Benjamin & Hannah Stacey,nee Feltis who had married in Wexford in 1853. Hannah (the mother) 2nd married John McLaughlin (in 1867) then 3rd married Jef Pierson (in 1872). On this marriage certificate her parents are recorded as Frank & Sarah Feltis.
I believe that you should look for death of Francis Feltis (snr) before 1865 as on the 2nd marriage of Ellen Feltis to John Stacey in 1865,her father Francis is recorded as deceased. Ellen had previously married 1st to Evan Miller in 1850.Both in Wexford.