Seat blocking work for me in general, I try not to book a seat in the front few rows though... for some reason some SENs will pick even a middle seat as long as they can sit in the 'preferred zone'. Altea theoretical seating will place SEN + companion on light fares in the 'zone' too, which leads to strange situations. The other day we go seated in BCDE automatically 🤦‍♂️