I agree with Often1 - I believe the in-laws should consult a local attorney in Greece to figure out their options. I found the following link:

http://europa.eu/youreurope/citizens...non-eu-family/

It states that a non-EU national may enter without visa if traveling with a EU citizen spouse and the traveler has an EU residence card. Since your father-in-law has close ties with your mother-in-law who is a Greek national, I think it shouldn't be much of a hassle to obtain a Greek residence card. Not sure if they have looked into this previously but I would focus my efforts on that. If the father-in-law obtains such a card, he can stay in the EU indefinitely.

Also, since father-in-law already overstayed, leaving immediately or flying back in a month won't make much of a difference. You might save yourselves a lot of money and leave their tickets alone. I would use the upcoming 4 weeks in figuring out how to obtain an EU residence card.

As to the 90-day rule, the airlines clearly indicate that all visa issues need to be resolved by the traveler and are not the responsibility of the airline, however, usually entrance requirements are checked at the point of departure. A diligent agent would have noticed that there is a 90-day limit on the stay of a non-EU citizen in Greece and noticing the return is more than 4 months away, should have pointed it out. If they had, your in-laws would have had sufficient time to modify their travel plans and depart the EU before August 12th.

I'm not familiar with Greek law but if your in-laws plan to visit Greece often, I would look into obtaining either Greek residence or citizenship for your father-in-law, so that this is not an issue in the future. Even if the procedure is more complicated when a Greek citizen gets married outside Greece, it should still be possible.

Finally, if you do decide to have them leave as soon as possible, US Airways flies from Athens to Philadelphia, I believe and then then can connect to Cleveland, so you get to skip passing through another EU country altogether and fly directly to the US. And I agree that if the overstay issue does come up when leaving Greece, it's quite helpful to have your traveling companion, i. e. spouse speak Greek, so you can address that and hopefully, get a more favorable treatment.

If the OP's parents want to deal with the leaving Schengen issue in Greece,another option would be to transit through London.Chaging flights to the USA will not throw up any immigration issues that way,apart from the overstay.

To OP:

First of all, don't do anything rash. Your FIL has already overstayed his 90 days and is in trouble (or will be) regardless....or he won't be.

There are several people advocating leaving directly from Greece instead of going through other Schengen areas, and others saying it doesn't matter. As a Greek and current Schengen area resident, let me offer that both views are correct. Legally, it shouldn't matter whether he leaves from ZRH, MUC, CPH, ATH, or any other Schengen airport -- he'll be in trouble regardless. But practically speaking, Greeks are much less likely to enforce anything strictly. This becomes especially true if you're going across a land border (since they're not as "official-ized" as the airport desks would be), are traveling with a native speaker, etc.

If there is a serious concern here, I strongly recommend following a previous poster's suggestion to go by land to Istanbul and fly from there (without connecting in a no-transit-zone Schengen airport -- if you're unsure, just avoid the Schengen zone altogether) after spending some time to see that amazing place. (For your Greek MIL, there are some great relics of the Byzantine Empire; might I recommend Hagia Sofia, Chora Monastery, and the Constantinople "Rum" Patriarchate?) Feel free to PM if you want to discuss further.

Hire a lawyer to deal with an "overstay" "violation" that hasn't and may not even be noticed by the Schengen passport control officials? Seems premature.

No reason to worry about a "ban" being substantive and enduring in a meaningful way when family reunification rights are intertwined with mobility rights in the way they are in this area. More reason to avoid a routing via Germany.

Fly via Italy or France or the Netherlands. As long as no visa was involved in traveling to the Schengen Zone on a passport of a country whose citizens may enter without a visa, the probability is extremely high of there being no problems.

After getting back to the US (or wherever the FIL legally resides), get a new passport and apply for the appropriate Schengen visa for use next time. Applying for adjustment of status for residency while in Greece after having appeared to have overstayed will more frequently be more of a problem or slower than what I noted.

Unfortunately you missed an important bit here - quoting from the above web site:

For the father-in-law to enjoy free movement in the EU the couple would first have to move to a different EU country and stay there for long enough for the husband to obtain a residence card. Once he has a residence card from a different EU country he is then free to stay in the EU with his wife under her EU Free Movement rights.

And I disagree with GUwonder (who normally gives good advice) that talking to a lawyer would be overkill. Lawyers are there to offer advice - and are much better placed to offer advice than a bunch of unknown people on an Internet forum.

As I see it, the OP's FIL faces three problems:
a) whenever he leaves Greece (or somewhere else in the Schengen Zone), the officials may (or may not) notice that he has overstayed and may (or may not) issue a fine or impose some other penalty immediately. Advice to go by land borders or to go via France rather than Germany address THIS problem - they may not notice and they may not care. But:

b) wherever and however he leaves the Schengen Zone, even if officials there didn't notice or didn't fine him, there is now a computer record of when he entered and when he left, and therefore a record that he exceeded the 90 day limit. (If he leaves without this being recorded, it's worse as his 'overstay' just keeps growing.)

c) In the future (OP said they do this trip every 3 years) he may be denied entry altogether, regardless of whether he was 'noticed' or fined on departure.

Advice on "they probably won't notice / they probably won't care" is not addressing the second and third issues.

FWIW, I did three trips to Switzerland in ~six months; the first two added up to 70 days. The third entry at ZRH, the passport control officer spent a long time looking at my file, and then I was questioned about whether I was going to stay more than 20 days. (I wasn't.) Sure, that was ZRH, this is Greece, YMMV, but there are records kept.

The stamping is more reliably done than entries and exits logged on shared databases. Even SIS use is so spotty that flagged docs are missed and SIS is what is primarily used when/if the passport was scanned. Entries and exists of ordinary tourists not generally recorded in SIS.

There are non-centralized national databases for some countries that do track entry and exit -- Greece paid for one -- but that data is not generally shared across the Schengen Zone.

There are Greek surface crossings that do use the Greek national database, which is why I mentioned exactly what I did.

I am communicating on this topic on the basis of various investigations that got frustrated because of how matters in this area work and don't work when it comes to tracking people entering and exiting the Schengen Zone.

There is some relevant info to be found in the following that confirms some of what I have mentioned:

http://europa.eu/rapid/press-release_MEMO-13-141_en.htm

Hiring a lawyer at this point to deal with an " overstay" "violation" is premature at this point. The OP's relatives will get more information but a fix for the "overstay" "violation" not noticed by the authorities? Not likely in a month.

If I were in the position of the OP's in-laws and using a US passport, I would route myself to exist the Schengen Zone at MXP/FCO, CDG or AMS and then apply for the appropriate status with a Greek embassy/consulate in the US once back in the US. I wouldn't be hiring an attorney at this point.

There is a difference between "hiring" a lawyer to take action, and paying for an hour of a lawyer's time for general advice. A local immigration lawyer will know the law (both EU and Greek law), and will also, in all likelihood, be able to give practical advice based on their experience.

Paying for an hour of a lawyer's time would, IMHO, be a bundle of Euros well spent.

(Here in the UK many lawyers charge a - relatively modest - fixed fee for an initial consultation. Does anyone know if it's the same in Greece?)

If the hiring provides peace of mind -- by providing additional information -- then go ahead. I just wouldn't recommend spending any money expecting a lawyer to fix an "overstay" "violation" -- one not yet (if ever to be) noticed by Schengen authorities -- before September 23rd. To increase the risk of the "overstay" "violation" to be noted, exiting Schengen from Greece or getting a lawyer involved to fix the issue are some ways to do that.

In Greece too it is possible to get a lawyer's advice for a modest fixed fee for an initial consultation, but it's not uniform across the legal profession there. If the lawyer says he's going to fix the issue by September 23rd, look for another lawyer. Legal fees in Greece are likely to be reasonable. It would be cheaper to get a new US passport and stick to plans as is and then apply directly with Greek consular officials for a longer-term status once back in the US.

If the OP's in-laws were to be found overstaying by the German authorities -- and the authorities may have to rely on the stamps -- and the German authorities care to fine them -- even they don't always care to do so -- they can pay the fine in Germany. Talk of a long ban for the spouse of an EU citizen is scaremongering. Talk of needing a lawyer to avoid that outcome, par for the scaremongering course. Hope that helps provide some background on why I responded as I did.

Wow, this is more help than I ever anticipated. Thank you for offering so many different scenarios and analyzing each meticulously. I am not sure as it stands now what they will do but I have a feeling they are just going to keep their original plans as is and wing it. My FIL is 83 and pretty frail. He is also the nicest person in the world and I honestly have trouble believing terrible things will happen. I have relayed many of the concerns shared by you guys and options to route out of different airports, get a new passport later and so on, and so I will keep you updated. This has been interesting!

I go to Switz. (entering via ZRH) often (but never more than 4 days at a time), and spaced out over several months--but my pp has lots of ZRH entry and exit stamps.
On a recent trip, the pp control agent, after looking at his screen and my pp, asked "is this the first time you are visiting Switz.?"

One never knows what will happen, but especially since this is a case of a US citizen returning to the US I think that if they play the "somewhat dottery old person" card they might just get a pass, if the agent even notices at all. Please let us all know what happens, and best of luck.

This is a good choice of action (do nothing, hope it all works out) but may I emphasize the need to say nothing to draw attention to themselves. They should NOT attempt to explain or justify or apologize unless they are explicitly "caught" -- they should simply look bored and tired and hand passports to whatever official, answer the perfunctory questions ("Where have you been? Why were you here?" "Greece, vacation"), and move on. Trying to be helpful in this case -- which many polite people want to do as a first instinct -- will only prove harmful in the long run.

Best of luck to them, and keep us posted!

Mikros,
I copy and pasted your reply to them. I will update the thread with any developments
Thanks again.

Perhaps it was a trick question to ensure you are the individual listed on the passport.