Attach invoices, collect vendor forms, request missing proof. Every one is ready to run, and you can adjust it in plain language.
Your reviewers get the vendor packet beside high-value purchase requests, or a clear list of what's missing before they decide.
Your bill reviewers get the supplier invoice and any mismatches together before they decide what to approve.
Your requester knows exactly what to add, and your approver can see why the bill is waiting.