...Your widow or widower can receive benefits at any age if she or he takes care of your child who is receiving Social Security benefits and younger than age 16 or disabled.
Your unmarried children who are younger than age 18 (or up to age 19 if they are attending elementary or secondary school full time) also can receive benefits. Your children can get benefits at any age if they were disabled before age 22 and remain disabled. Under certain circumstances, benefits also can be paid to your stepchildren, grandchildren, stepgrandchildren or adopted children....