The official family categories concern the actual qualifying spouse and unmarried children under 21, not a rule that all surnames match. Different naming practices still require clear relationship evidence. Review the real documents and individual eligibility rather than treating a shared name as enough or a different name as an automatic obstacle.
Connect each person to the proposed household accurately
Identify the relevant marriage and parent-child records and any legal-name history that explains the differences. Ask counsel about any relationship question the records do not settle. The official site recommends including joining family members initially for program benefits.
Neither a family naming pattern nor one person’s payment guarantees approval for the others. Two mistakes sit on opposite sides of the same question. One family assumes a shared surname is enough and prepares nothing further; another assumes different surnames are a defect and starts looking for a way to make the records match.
Both are working from names when the category works from relationships and ages. Take each proposed member separately: what is the relationship, which record establishes it, and what is that person's age and marital status now and at the expected time of the steps ahead. A child approaching twenty-one and an adult child are different questions, and a family that discovers this late has lost the time it needed.
Ask counsel about anyone whose position the records do not settle plainly.