Install NemoWorks Sync alongside MyWorks QuickBooks Desktop Sync. Do not remove MyWorks yet.
On the Audit page, Import from MyWorks previews, then copies its product, variation and customer pairs. Settings are not copied: choose them in the setup guide. MyWorks itself is left untouched.
Run the setup guide; your QuickBooks lists are read on the first run.
Run the Audit for the last month or two. Orders MyWorks already booked show as “already in QuickBooks” and are never booked again.
If MyWorks booked payments straight into the bank, use Fix past payouts (paid plans) for the months your bookkeeper has not reconciled yet.
Switch MyWorks off in its own settings, remove its row from the Web Connector, then switch on Write to QuickBooks here.