Transit in Schengen airport without ticket

Question

I have a friend visiting Europe. She was issued a Schengen visa with one entry. She flew from Hong Kong to Athens via Singapore.

She had booked a separate flight from Athens to Barcelona via Sofia. Only after she arrived in Sofia ready to take plane to Barcelona she was told she can't enter Spain as her visa has been used up.

Will she able to take the return flight to Hong Kong from Athens?

After arriving from a non-Schengen country to Athens airport you either go through the Schengen border check or the transit zone.

The problem is she is unable to check in online. I'm wondering if they allow her to take the flight.

Normally she would get a boarding pass at the departure check-in, but for that she needs to enter Schengen.

Answer 1

Your friend should be able to transit in Athens from Sofia to Hong Kong, provided that she is traveling on a single booking such that she doesn't need to pick up and re-check baggage. (She would need to enter the Schengen are in order to reach the baggage claim).

Traveling on a single booking, she should get boarding passes for both legs when checking in in Sofia; there's no need to visit a check-in desk at Athens.