Hi Marie, I came across your post while searching another Morrow in my family tree. Your Elizabeth Morrow married to John Rice is in my family line. Her brother John born Dromore c.1825/26 who is my gg grandfather, married Letitia Johnston, 1850 Donegal, daughter Letitia Morrow born Donegal 1880, she married my g grandfather James Morrow in 1904, (yes both Morrow's), Their son John, was my grandfather. I am currently researching James Morrow's (born c.1880) family line, and know his father was also James and that's when I saw your post.
Elizabeth Morrow, Father, Thomas Morrow b.1797 m. Elanor Downey. Children Elizabeth & John plus Sarah 7/12/1833; Alice 20/12/1832; James 29/01/1825.
Thomas Morrow, Father John Morrow, mother Elizabeth Burns. I have to clarify all this, but your search for families in Donegal also gives me hope that this is correct.
Hope this helps you in some way. Best Regards Terry Morrow