Treatment of 'Debit/Credit note' in GSTR1

Dear experts,
Please clarify the following: 

If sales return from the (B2B) customer, i.e. credit note issued by us where to show in gstr1 (Reduction/Adjust/Decrease the tax liability from the earlier amounts paid through GSTR 3B). 

If additional charge to the customer(B2B), i.e. debit note issued by us where to show in gstr1 (Increase the tax liability apart from the earlier amounts paid through GSTR 3B). 

Treatment of the above transactions in GSTN system. These are the accounting entries.