Teacups, a regular poster here, gave a very informative post on Chewa names once. I'm sorry I'm not good at searching, but perhaps someone else can find it for you.
Congratulations and good luck with your twin sons! I love that you want to use their native names. It will be very distinguished and distinctive on them. Try saying that three times quickly. :-D
P.S. I can't help putting in a pitch for the middle name of
Thomas for one of them. It means twin. Just a thought.