nó: Oibrí oifige ata inti.
nó: Ta sí ina oibrí oifige.
when you was doing families didn't you miss out the grandchildren eg
Grand daughter = Gariníon and grand son= Garmhac
and what about this one grandparents =Seantuismítheoirí
Ta sí ina hoibrí oifige.
The possesive form adds a séimhiú to a word with a vowel at the start if it's for a female :)
YoungSpoon is right about the sentence. You have to add a h to the oibrí because you're talking about a female. Technically speaking, this isn't a séimhiú and it's kind of confusing to use that term because when you're talking about females with constructions like this, you DON'T add a séimhiú to consonants.
Tá sé ina ailtire. He's an architect.
Tá sí ina hailtire. She's an architect.
Tá sé ina dhochtúir. He's a doctor.
Tá sí ina dochtúir. She's a doctor.
In the modern spelling of Irish, we associate h with séimhiú. This is really quite recent. The h began to come in a couple of hundred years ago but didn't get wide acceptance until the language reforms in the mid-20th century. Before that, the séimhiú was always indicated with a small dot over the consonant.
There is a slight difference of meaning or implication between Tá sé ina oibrí oifige and Is oibrí oifige é. The former carries the implication that this is a temporary state or that he used to do something else or will be doing something different next year. The latter is much more neutral and just means that he is an office worker. As you might expect, the ina oibrí version is more often found with expressions of time.