If your spouse is working and earning more than the exempt amount of earnings (2010 is $14,160) then her earnings above the exempt amount would be deducted 2 for 1 from her monthly benefit. May not have been a good idea for her to file a claim. Or all of your children were ages 16, 17 and 18 (unlikely but possible) and she could not be eligible at all.

Regardless, the family max is a pie that is divided among all the beneficiaries. The pie doesn't get bigger for more family members but each person's piece gets smaller. If there is only one person left on the record (youngest child) that child cannot get more than 1/2 of your (the disabled person) benefit. If your second youngest reaches age 18 and your youngest is still under 16 and your wife is not working (or earning under the exempt amount), then it may be financially advantageous for her to file a claim.

Spouses have to either be over 62 or any age and have your child-in-care under age 16 in order to be paid benefits.