What the append step does
The example stacks a northern and a southern supplier list. The southern file has its columns in a different order and an extra lead_days column. Matching by name puts sku, name and unit_price in the right place; lead_days is added as a new column and is missing for the northern rows rather than filled with a guess.
The step’s ledger shows the exact header mapping used and counts: rows before, rows appended and the total. If you choose to drop unmatched columns, the step reports that as a loss.
Every row keeps a provenance ID such as B:2 (source B, record 2). Export the provenance report from the Export tab to keep that link outside the app.
Questions
How do I add more files?
Use “Add file” or drop several files at once. Each gets a letter (A, B, C…). Add one Append step per extra file, or use them in joins and comparisons.
What if two columns share a name?
Duplicate headers are matched in order of appearance, and internal column IDs keep them distinct throughout the recipe.
Does merging remove duplicates?
No. Appending only stacks rows. Add a Deduplicate step afterwards if the files overlap, so you can review the duplicate groups first.