family structure; family composition; family makeup
申込書に家族構成を記入する。
Fill in your family composition on the application form.
核家族化が進み家族構成が変化している。
As nuclear families become more common, family composition is changing.
家族構成によって住宅の間取りを選ぶことが多い。
People often choose a floor plan based on their family composition.