Asked two attorneys and they didn’t know the answer. Have asked the appropriate Greek and US agencies and have received no reply. I’m asking here bc these are experienced, knowledgeable travelers.

We have a complicated trip with lots of moving parts so my plan at the moment if all else fails is to fly ATH-IST on day of expiration and return the day after. That’s really the best I can do short of changing the entire trip (still looking at options to do that though). His ticket out of Greece to UK then onwards to US is dated one week after the re entry to Greece. But we will be traveling by ferry and plane within Greece during that week.