The problem here is that “immediate” and “extended” family in US immigration do not mean that same thing as those terms mean in any other context, and both are what would be considered immediate family of the sponsoring citizen or permanent resident in other contexts (parents, spouse/fiance, children, and siblings, and nothing further.)

“immediate family” in US immigration refers to a spouse or fiance of a US citizen, certain minor children of US citizens, and parents of adult US citizens.

“extended family” refers to children (including adult children) of US citizens not considered “immediate family”, adult siblings of US citizens, and spouses and children (including adult children) of permanent residents.

This creates and immense opportunity for lying by way of equivocation, where a statement which is accurate only because the definition of a key term in the context of the statement is different than what the audience understands it to be is used to convey a message which depends on the audience interpreting the statement according to a different definition of that term.