Also, she should get some fairly cheap Stafford loans, and maybe a Perkins. If you do take out other loans, be consider the Federal PLUS loans.
They can be consolidated with the other Federal Education loans for an overall lower interest rate, and the rate will likely go down after a couple of years of consistent payments.
Private loans will be much more expensive and cannot be consolidated with the Federal loans.
I made a boo boo and took out one of the private loans, and now will be over borrowing on FED Plus loans to pay it off and get everything back into the FED loans for consolidation in a couple of years when the kids start to graduate. Then they can get great jobs and help with the payments.
I would avoid tapping your TSP unless there is no other way, as it is a strong source to grow capital.
It is worth more as investment than as bank.
However, you gotta do what you gotta do. When I get to retirement, I might decide to pay off these loans from TSP just for the psychological relief of being done with them, but it probably would not be my most prudent move financially.