Use this when the user wants to stack or append many spreadsheets into one: "combine multiple csv files into one", "merge 12 monthly excel files", "combine excel files with different column names", "append these exports into one sheet", "combine all sheets into one". Takes 1 to 24 CSV, TSV or .xlsx files (or pasted tables). Aligns columns by identical name, then same name with different case or spacing, then a synonym table (Amt = Amount, Txn Date = Date, Memo = Description), then fuzzy spelling matches that are listed for confirmation; a specific column is not folded into a more general one (Spouse First Name stays separate from First Name). Adds a Source file column, decides day/month order once per file, reads EU number formats, removes total rows and repeated headers (listed), and reports each column decision. Returns an Excel workbook (Combined, Column mapping, Files, Excluded rows, Summary) and a CSV. Does not join files side by side on an ID (use join_spreadsheets) and does not do mail merge.