Gst r 1 and credit note

My job work turn over in the month of May 75 lack I have made eway way bill. and I have file 3b and deposit tax amount. but party not accept some bill which amount is 30 lac . and party said u can made these bill in the month of Feb than I am after adjustment of tax filed 3b of Feb month. Now I want to know how I file may month gstr 1. can I will issue credit note for this invoice and file gstr 1.