Every time a customer sends goods back, we fill out a custom Google Form. Some of the data we type is already sitting in our sales-invoice Google Sheet, so I want a small Google Apps Script that pulls that information and drops it straight into the form for us. Here’s the flow I have in mind: We type an invoice number in the form We click on prefill data The data in the relevant column gets filled based on data base of sales The script must: • Read from the Google Sheet that holds every invoice. • Map those columns to the matching Google Form fields (product code, description, customer name, address, etc.). • Handle typos or missing invoice numbers gracefully with an alert. • Be clearly commented, so I can tweak field names later. • Include a brief, step-by-step guide on how to install, authorise, and use it—I’ve never used Apps Script before. If you can add small extras such as logging or the option to email the pre-filled link automatically, let me know, but the core automation above is what I must have to cut the manual copy-paste work.