How spreadsheets drift after the invitations go out
The guest list usually begins as a spreadsheet, and for a week it behaves. Then a yes arrives in the family chat and gets ticked off a mental list. Then a partner is added verbally and noted in nobody's column. Two weeks before the event you have three sources of truth that disagree, and reconciling them means rereading every conversation a party has already moved past.
The fix is to stop maintaining a list that sits beside the invitations and let the replies compose it. Send guests to a page with a reply button, and each response writes its own line: who, whether, how many, what they eat. The spreadsheet was always trying to be a mirror of this.