Any experience how Spanish border control @ MAD would treat my wife who might overstay her 15-day visa by 4-days, before we'd attempt to board our flight back to USA? I'm an American and will be with her, this would be mid-July.


Additional details for context:
-My wife (US Permanent Resident w/a Chinese passport) received her Schengen single entry visa yesterday, but the 'Duration of Stay' reads for 15 days, which does not align with our departing/returning flights which would make our stay 19 days.
-The visa was issued by Iceland (after a lengthy processing period), which is where we will enter the Schengen zone.
-Our return flight to the US is out of Madrid on Iberia to SFO
-In between, we have to attend a wedding in Sweden and a memorial for my 93yo grandmother in France w/my aunt (her passing was after we applied for her 15-day visa, hence last minute extension).

-To remain compliant, I may still attempt to extend the visa through the Icelandic consulate, but the process was surprisingly fraught with delays and confusion (due to the VFS Global third party processing service), so I am not optimistic Icelandic consulate would approve, let alone resolve it before we depart US next week.

Question is, should I:
A) Attempt to rebook our return within the 15-day duration (which may cost $3k due to lack of close-in award availability)

B) Roll the dice and hope for a nice customs officer before our departure at MAD?

Thanks!