May be able to answer your question.

[2) Born outside of Ireland to Irish parent or Irish born grandparent

According to Section 7 of the Irish Nationality and Citizenship Act 1956 (as amended in 2011) a person is an Irish citizen or can become an Irish citizen by foreign birth registration if:

Your parent was an Irish citizen born in the island of Ireland , you are automatically an Irish citizen, irrespective of where you were born
You were born outside of Ireland to a parent who was also born outside of Ireland whom you derive Irish citizenship from, you are entitled to become an Irish citizenship if you register your birth through the Foreign Births Register
You were born outside of Ireland and your grandparent was an Irish citizen born in Ireland, you are also entitled to become an Irish citizen by registering your birth through the Foreign Births Register
If your grandparent/s and your parent/s were both born outside of Ireland, you may only be entitled to become an Irish citizen by having your birth registered in the Foreign Births Register, however, your parent through whom you derive Irish citizenship must have become an Irish citizen by being registered in the Foreign Births Register before you were born.
If you were born after your parent registered their Irish citizenship in the Foreign Births Register, you are not entitled to become an Irish citizenship through descent}(http://brophysolicitors.ie/irish-citizenship-by-descent-and-foreign-birth-registration-are-you-eligible/)