Google Sheet Contact Update Form

I have two Google Sheets: one holds existing customer records, the other is my source of fresh contact information. I need a clean workflow that lets me review each new or revised entry through a simple form and then write the approved details—name, email, phone, and any other contact fields—into the master sheet without overwriting unrelated data.

Here’s what I need from you:

• Build a user-friendly Google Form or in-sheet sidebar that pulls rows from the source sheet one at a time, shows every contact field clearly, and lets me confirm or edit before saving.
• On submission, insert new contacts or update matching rows in the master sheet while keeping its current structure intact.
• Add lightweight Google Apps Script logic so duplicates are detected by email or phone and flagged for review.
• Provide short comments in the script plus a one-page setup guide so I can reconnect the form if I move the spreadsheets later.

Nothing fancy beyond that—just a reliable, manual-through-a-form solution that turns the second sheet into an easy staging area for my customer contact updates.