My question is about adding vocals to a loop station with only 2 inputs

Question

I'm a performer/entertainer & wish to loop my vocals occasionally but at the same time use my looper to capture my guitar signal & electronic drum tracks separately. My loop pedal only has 2 inputs which are occupied by my guitar & drums. I need an option to add vocals to my loops when required on a layered basis which my looper is capable of doing. It's a Boss RC1 pedal I use.