Do all eligible federal student loans have to be included when you consolidate?

Asked by archlydia
I consolidated my undergraduate federal student loans a while back fixed @ 3.25%. I now have two seperate graduate student loans (also federal) that I would like to consolidate at a fixed rate so I can pay them off more easily. My undergraduate loan is a higher amount than my graduate loans combined and at a very favorable interest rate. Can I consolidate only my two new loans without including my low interest loan? I would not go through a private company, but rather through "Direct Loans." Having a singe payment is not my priority, I am looking for a fixed interest rate (preferably the lowest possible).