I love these sentences. Imagine the situations for some of these. You have a deer...
My daughters middle name is Fianna. But it isnt meant to be deer(plur.) When i looked it up, it essentially meant a female member of Fionn Mac Cool's warrior band. :p
Fianna is the plural of fia. However ainesmomma in relation to your daughter's name the warrior band of Fionn MacCool were called Na Fianna (The deer (plural)) and it has come to mean warriors or defenders (can't remember the exact translation) in more modern times with the adoption of the word as a translation of the Irish national Anthem 'Amhrán na bhFiann' (in English 'A Soldier's Song') and the naming of the political party 'Fianna Fáil'. So the translation you found for your daughter's name is also right. Irish names are often spelled in the tuiseal guinneadacht form of the noun.
"Fianna Fáil", "The Soldiers of Destiny". I've often thought this sounds more like a band than a political party.
Fianna in Fionn mac Cumhail agus na Fianna, Fianna Fáil etc is actualy the plural of Fiann - a group of warriors, not of fia (originally fiadh).
My little sister calls me 'fia' and doesn't know it's Gaelic for 'deer'
Tá fianna i do ghairdín agat (I'm assuming you're using 'yard' in the U.S. sense).