missed sale bills in Dec 2017

While filing GSTR 3 B and GSTR 1 of Dec 2017 few sale bills were missed..Can the same be incorporated in March Returns ..both in GSTR 3B and GSTR 1...What about Document summary in GSTR 1 ..the dealer who has purchased from us has shown December itself.....In the same month in one sale bill a mistake has taken place..Taxable value was shown less by RS 50000 in one of the sale bills...Please guide...