Do not include the March 2020 (₹7 Lakhs) purchase in the FY 2020-21 GSTR-4, as it belongs to the prior period when the taxpayer was a Regular filer. File the GSTR-4 based solely on the sales turnover and inward supplies generated between April 1, 2020, and March 31, 2021, under the Composition Scheme, without claiming any ITC.