What happens if i dont board flight booked through Free at seas BOGO promo

[kaybeebee]

So, we have our flights assigned through NCL free at sea program with a 1 day early arrival deviation. When I go onto Delta website it allows me to change my flight to the day before ticketed fare ( 2 day early). Does anyone know if this would list me as a no show with NCL and/or cancel the return flight? Return is on a different airline