I've databased alot of organizations and wrestled with your issue.

IMHO

The Allen Browne approach referenced by Dennis is very sophisticated,
versatile, powerful & abstract. (that's what you get from someone who is
one of the smartest on the planet at this) Those are 4 things that you might
want to avoid unless you needed them, which you probably don't.

So then the question becomes whether you need a full "two tier" system (with
Families and People both being entities) vs. just "stretching" a one "tier"
system (people). You probably need a two tier system.

And so basically that means do what Dennis said. Except that I think he
misread yo on one point....I think you intended your "head of household"
idea as an alternate to the two tier method.....and so now you don't need it
and he was trying to add it. (or maybe I misread you :-) )

So, recapping, (change all names as desired) make a "Families" table, (PK =
autonumber "FamilyID" field. Make a "People" table with an integer (FK)
"FamilyID" field. Link the 2 "FamilyID" fields.

You main data entry form will be a "Families" form with a datasheet style
"People" subform.

Every person belongs to a family, even if a "Family of One"

So, to enter a person, go to that main form, find or enter their family,
then enter the person in the Person subform.