SIM868 GPS/GNSS and Arduino Nano

I want to design a board for SIM868 with ATMega328(nano) with Arduino bootloader.

I want to use single UART to interface SIM868's GSM and GNSS with Arduino Nano

I have gone through some hardware designs and came across this

in the above URL on page 18 "All-in-one" mode is mentioned.

I want to be sure that after using the same method mentioned in All-in-one mode will I be able to use the GSM and GNSS via single UART of Arduino Nano.

If not, then how can I achieve that?

Thank you in advance.

Hi gauravntpl,
did you find any solution?
i'm stuck too...