It should be checked rather than accepted. The official material has described amounts per participant, and a single family figure may be a simplification, an estimate, or a term that has since changed.
A single family figure deserves a source
The instinct to quote one number for a household is understandable, and it is exactly the kind of simplification that goes wrong. Ask which official text the figure comes from and read that text. Ask whether it covers a spouse and each child separately or as a group, and what conditions attach to each person.
Ask what happens if one member of the family is assessed unfavourably while the others are not, and whether anything paid on their behalf is affected. Then ask when each person's circumstances are assessed, because a young adult in the household may be treated differently depending on the point at which age is measured. None of these questions is answered by a price.
They are answered by the current official material, read directly, and a household that cannot locate an answer there should treat the point as open rather than settled.