Missed B2B Invoice of FY 2018-2019

I missed one B2B Invoice of fy 18-19, this invoice was not shown in GSTR 3b nor Gstr 1 of fy 18-19. Also I did not rectified this mistake in fy 19-20 upto sept return.
now in annual return how I will show this missed Invoice?? and after paying liability in annual return can it be seen by receipent in his Gstr 2A??
plz help
Annual return for me is optional.
how can I rectify this mistake??