The "Family Maximum" ranges from 150%-180% of your FRA benefit. It is for beneficiaries who have a young family. Children under age 18 each receive a benefit as does a spouse until the youngest is age 16.
In my case when I started at age 62, My spouse was 34 and my sons were 10 and 7 mos old. Each of my sons gets a check equal to a little more than 1/2 my check. My spouse would also get a check, but has never lived in the USA and does not have a SS# (required). We will move to the USA this year and when my oldest son ages out, my spouse will qualify and receive benefits until my youngest turns 16 or if we have more children in the future, until the last born turns 16.