Michelle Obama listed daughters Sasha and Malia as 'Senior Staff' on Africa junket

From Thomas Lifson at American Thinker:

[I]t is worthwhile noting that just a couple of years ago the First Lady officially termed them "Senior Staff" for official purposes. We know this only thanks to a Freedom of Information Act (FOIA) lawsuit filed by Judicial Watch. The organization had at first requested the information pursuant to FOIA, but when denied, was forced to sue. .......................

The professed purpose of Michelle Obama's trip to South Africa and Botswana was to encourage young people living in the two growing democracies to become involved in national affairs; and during her scheduled stops in Pretoria and Cape Town, South Africa and in Gaborone, the capital of Botswana, the First Lady used the opportunity to speak on education, health and wellness issues.The trip also included such tourist events as visits to historical landmarks and museums, plus a nonworking chance to send time with Nelson Mandela, a meeting that Mrs. Obama described as "surreal." The trip ended with a private family safari at a South African game reserve before the group returned to Washington on June 27."This trip was as much an opportunity for the Obama family to go on a safari as it was a trip to conduct government business," said Judicial Watch President Tom Fitton. "This junket wasted tax dollars and the resources of our overextended military. No wonder we had to sue to pry loose this information."

What is the story behind listing the daughters as "Senior Staff"? Are there regulations that would require reimbursement to the government for their travel if they were listed as children?

It makes sense that the Obama's would be gaming the system to avoid paying for their kids to be on the trip. The reality is that it really doesn't cost that much more to add the kids, even the Moochelle's Mom, niece, and nephew. The real question should be not so much that there are all the extra add-on, but why was the trip necessary in the first place?