Interest Payments

Hi everyone. I’m one of the lucky SAVE plan borrowers that is currently sitting in limbo. I’ve decided to make interest payments every month so my balance doesn’t continue to accrue, rather than switch plans, at least for the mean time. Don’t have the extra cash at least right now to be making payments. How do I go about paying just the interest amounts? I have 9 federal loans with varying interest rates. Do I need calculate the interest for each loan for 30 days and then add them all up? Then just make a custom payment on Mohela’s website? Thanks for any tips!