I think this doable but not 100%. I have the beat buddy plugged into a pair of studio monitors using stereo cables. I’d like to also plug my guitar interface into the the beat buddy using my guitar interface and bias fx software. All mixes is output to studio speakers. Any issues with this setup?
To answer I’d need some more info on cables you are planning to use and maybe some drawings 
BB has two mono inputs and two mono outputs + headphone stereo output 