Credit not missed in GSTR 1&3B, effect in GSTR9

piyush (ca) (79 Points)

10 September 2020  
In case of sales if some credit notes forget to taken in GSTR 3B and GSTR1 of F.y. 2018-19
How to show in GSTR 9?
Can we show all this credit note in Table 4 box no. I?