whole family; all the family
Refers to every member of a family together, often used in formal greetings or announcements.
The whole family wishes you good health.
New Year's greetings from all the family.
家族 means 'family' in general, while 家族一同 explicitly means 'the whole family' or 'all members of the family'.
Compound of 家族 (family) and 一同 (all members, everyone).