Excel-to-TallyPrime Invoice Import

I keep my sales invoices in a single-sheet Excel workbook where every row is a line item and the columns track invoice number, date, customer details, item description, quantities, GST figures, round-off, override amounts and the voucher mode. We are already using third party tempelate to import data from excel to tally prime. But due to recent change in taxes we need corrections and now tally directly allow import from excel so no third party templete is needed.

Your task is to build a tempelate in tally which can import data from excel, recognises when a new invoice starts, and posts each voucher into TallyPrime with item-level detail intact. GST calculations, round-off values and any overridden amounts must match the source file exactly.

Acceptance criteria
• All invoices from the sample spreadsheet appear in TallyPrime with correct customer, item, tax and total figures.
• No duplicates or missing vouchers.
• The tool works on future files without code changes beyond selecting a new workbook.

Tell me how you plan to tackle the mapping and how quickly you can supply a tested, ready-to-run solution.

Sample excel file attached but it will need little changes.