WI: Spain can't conquer Luzon because its discovery by Portugal is a common knowledge

From what I have read there is actually a Portuguese exploration in Luzon prior to that of Legaspi by Pero Fidalgo, what if this becomes a common knowledge in Portugal and Iberia, I think Spain would have likely kept Don Carlos alive due to him being the heir of Portugal after Sebastian I in this scenario so that they could conquer Luzon after Don Carlos becomes King of Spain so the conquest would happen in the 1600s instead of the 1500s.

This would also mean that if Spain conquers Luzon in this scenario it would be under the Portuguese crown not the Castilian Crown.