One timeline per account, and who keeps it honest

Every team that has tried a shared account record has watched it rot. The record is accurate for a month, then somebody handles a call outside the system, and after that nobody quite trusts it.

Copying is the failure

The rot always starts at a copy step. If a message has to be pasted in, a file attached a second time, an invoice number typed somewhere, then the record depends on discipline — and discipline loses to a busy Tuesday.

So there is no copy step

Mail, tickets, files, invoices and renewal dates arrive on the record from the systems that already hold them. Nobody is asked to log anything twice. What a person adds by hand is the part only a person knows: the note about why the customer sounded annoyed.