The problem this solves
SES doesn't want the same stay reported twice. If a previous tool already filed a booking's guest-registration report (RH) with SES, Checkinea must not file it again — but it should still take over the traveler report (PV), which is filed after each guest checks in, since that part of the job is Checkinea's from here on. Migrating cleanly means telling Checkinea which bookings the old tool already covered, without losing PV filing for them.
Marking a whole channel connection as already reported
When you connect an Airbnb or Booking.com channel for a property you're migrating, its Channels tab has a toggle: "Existing bookings were already reported to SES by a previous tool." (Vrbo connections don't show this toggle.) Turn it on only if you're switching from another tool that already filed RH for that listing's upcoming bookings.
This only affects that connection's very first sync — bookings found in that initial sync are marked as reported elsewhere; anything the connection picks up afterwards files through Checkinea normally. This includes Booking.com bookings that first appear as a booking candidate rather than a full booking. Disconnect the previous tool from the listing first, so the same booking is never filed by both.
The traveler report (PV) is unaffected — Checkinea still files it after each guest checks in.
Marking an individual booking
If a booking wasn't caught by the channel-connection toggle (or you're not using channel connections for it at all), open the booking and use "Already reported in SES? Click here." RH and PV are marked separately, each with its own confirmation, since a previous tool may have filed one but not the other.
Evidence: the previous tool's lote UUID
When marking a booking as externally reported, you can optionally record the previous tool's lote UUID — the batch identifier SES returned when the previous tool submitted it. This is stored as evidence against the marking and is checked later; it isn't required to mark a booking as external, but it's worth adding if you have it.
Filing anyway
If you marked something as external by mistake — or decide Checkinea should file it after all — use "File through Checkinea instead." For RH this queues a real filing, which can duplicate what the previous tool reported if that filing genuinely happened, so only use it if you're sure. For PV it reopens the guest's check-in step so a real traveler report can be filed once check-in completes.
What it looks like afterward
A booking marked as externally reported shows the status "Reported by previous tool." For what the different SES statuses mean in general, see SES statuses.