Check the payment record and application entries for each person, then confirm through the official channel rather than assuming. Each joining legally married spouse and each unmarried child under 21 carries its own US$15,000 processing fee and a US$1,000,000 gift, so a single payment of US$15,000 covers only the principal.
Confirming who is on the file, not guessing
Suppose a hypothetical applicant paid once, believing his wife and 19-year-old daughter were attached. The way to test that is the record itself and the official contact channel, and then the instructions USCIS sends about how family members are handled — not an assumption that every relative needs an independent I-140G. Including family at the outset is officially recommended for program benefits; adding someone later is neither impossible nor free.
Verification here means asking a party that keeps a record, not asking someone who was present when you paid. The application entries and the payment record are the evidence of who was included; a spouse's recollection is not. Check both, then confirm through the official channel.
Note where responsibility for each person's costs falls: each joining legally married spouse and each unmarried child under 21 carries its own processing fee and its own gift obligation, so a household of three carries three sets of obligations rather than one shared between them. Hypothetical example: the owner of a tree-care business adds a second child later and finds that the cost attaches to that child's own place in the process.