How to use the mic array and the on-board mic simultaneously?

I’d like to ask how to use the mic array and the on-board mic simultaneously? Since it seems impossible for me to get audio data from the mic array directly via MaixPy API, I tried to get audio data from the on-board mic while using the mic array to get sound direction. But it doesn’t work. I guess there may be some I2S interface conflict between the on-board mic and the mic array. But it is said that the CPU supports 8 mics and 3 I2S devices, and the mic array contains 7 mics serving as 1 device. Could anyone helps me out? Thanks a lot~