"We are learning as a small group and have a difference of opinion with regard to family members and possession. I understand the article should be omitted for close relatives unless they are pluralised or have an adjective but which relatives are classed as close. I understand it it omitted for mum,dad,brother,sister,children,aunt,uncle, but others in the group extend this to grandparents, in laws, cousins and nieces nephews etc. can you please clarify exactly which relatives should omit and which should include. Many thanks!"
It is true that when the possessed noun is a specific family relative the definite article is dropped, as in English, and then we use to say: "Mio padre"(not “Il mio padre”), “Mia madre” (not “La mia madre”), "Tua sorella"(not "La mia sorella"), "Nostro cugino" (not, "Il nostro cugino"),etc., unless these expressions are accompanied by a qualifying adjective such as "caro", "bello", etc. as in e.g. "Il nostro bel cugino"(our beautiful cousin), "La mia cara nonna" (my dear grandma).
So, it is true that with family members we do not use the definite article unless we are talking about many, as in “I miei fratelli”(my brothers), “Le sue sorelle” (his/her sisters), “I loro bambini” (their children), etc., whereas we say for example “Mia sorella” (my sister), “Mia nonna” (my grandmother), etc. when we are talking about only one relative.
Moreover, the definite article as well as the possessive adjective agree in gender and number with the noun possessed, not with the possessor, so that we say e.g.:”I miei genitori” (my parents) where “i miei” agrees with the masculine plural “genitori”; “la loro zia” (their aunt) where “la loro” agrees with the feminine plural “zia”, etc.
To sum up, here’s a table that provides many examples of the correct use of definite articles and possessive adjectives with family members:
1)When used in the singular, the following nouns have the definite article:
“Il mio bambino”(my child), “Il mio papà” (my dad), “La mia mamma” (my mum), though in colloquial informal language we can also say “Mio papà” and “Mia mamma”.
2)When used in the singular, the following nouns usually omit the definite article before the possessive adjective:
“Mio padre”(my father), “Mia madre” (my mother], “Mio fratello”(my brother), “Mia sorella”(my sister), “Mio cugino” (cousin), “Mia cugina”(my female cousin), “Mio zio” (my uncle), “Mia zia” (my aunt) , “Mio figlio” (my son), “Mia figlia”(my daughter), “Mia nonna” (my grandmother / grandma), “Mio nonno” (my grandfather/grandpa), “Mio suocero” (my father-in-law),”Mia suocera “(My mother-in-law),”Mia nuora”( my daughter-in-law), “Mio genero”(my son-in-law) , “Mio cognato”(my brother-in-law), “Mia cognata” (my sister-in-law) , “Mio nipote”(my nephew/grandson), “Mia nipote”(my niece /granddaughter).
3)When used in the plural, the following nouns include the definite article before the possessive adjective:
“I miei suoceri” ( my parents-in-law), “I miei fratelli”(my brothers), “Le mie sorelle” (my sisters), “I miei zii” (my uncles), “Le mie zie “(my aunts), “I miei bambini” (my children), “I miei nonni” (my grandparents), “I miei generi” (my sons-in-law) , “Le mie nuore” (my daughters-in-law), “I miei cognati” (my brothers-in-law), “Le mie cognate” (my sisters-in-law), “I miei cugini” (my cousins) , “Le mie cugine” (my female cousins), “I miei nipoti” (my nephews/grandsons) , “Le mie nipoti” (my nieces /granddaughters).
Hope I have clarified which relatives must omit and which must include the definite article. Should you have some doubts, feel free to ask me again.