Good name for a singing duo/trio?

Hi! my friend and I are planning on forming a singing duo and we might include another girl and form a trio, but we haven't decided yet. My name is Kathryn and my friend is Olivia, and the third girl we were thinking of including is named Audrey. We were interested in doing arrangements of relatively recent music, such as songs by the Beatles, etc. and modern-day songs from Glee and such. I need a name for a duo and also one for a trio(we haven't decided which we are being yet). Any ideas? :)