Originally Posted by ISTFlyer

There are dedicated passport booths for international-domestic and domestic-international transfer and they are usually empty. The transfer is doable and you should have enough time to do the connection, however, no one could guarantee that your flight from ATH wouldn't arrive at a gate which would require a longer walk to the passport control point, so you might end up walking kilometers inside the airport. If your mother requires assistance due to a knee injury, you could ask for mobility assistance from TK.