Difference between notre and nôtre
Notre is a possessive adjective and can be easily replaced by nos in plural.Nôtre is a possessive pronoun. It is always after le or la. In plural, il bacome nôtres.
To sum up, put the sentence in plural to make the difference.
Un membre de notre famille
==> un membre de nos familles
c'est le nôtre
==> ce sont les nôtres
Note : same for votre and vôtre