SKG-AMS has been added for the summer season. They started operating the route this winter, but until last week it was not available for bookings after March 28. It now is, though pricing from ATH (via SKG) is pretty crazy high. From SKG pricing is actually quite low, I was able to score a business class flight - just after Easter - for 175 euro. With a cheap ATH-SKG feeder flight this does unfortunately mean having to self-connect.

For the ATH-AMS route there still is only the single early morning flight currently. The second daily flight that operated last summer, and this current winter, is not available at all.