Bring the Desktop export you already have.
In QuickBooks Desktop: Reports → Sales → Sales by Rep Detail, then Export to CSV. Drop it here and we'll read it back to you: which reps it names, how many documents carry a rep, and the revenue behind them. No QuickBooks connection, no account, no card.
Your Sales by Rep Detail export.
Want us to dig into it properly?
The checks above are the ones we can run in a second. A person looking at the actual file finds more: odd exports and rep records that drifted apart over years, splits that were never meant to be splits. If that's useful, leave an email and we'll do it and write back.
Only if you tick the box. Without it, your file is parsed for the reading above, immediately discarded, and nothing is stored or sent anywhere else.
What this does and doesn't tell you. It reads the file only; the picture Desktop had. It cannot tell you what survived the conversion, because that needs your QuickBooks Online data to compare against; connecting your company turns this into the full migration check, which reports per document whether the rep came through. Your file is parsed and discarded; we don't store it.
The written guide, free and useful on its own: what the migration does to the rep field.