I fail to remenber in wich thread this thing has been discussed but the answer is no.
You have always to palace your units if your IC has the capacity.
Say I want to invade Manchuria as the US. In the sea zone surrounding japan is one destroyer. Can I have 2 separate battles one for the Sea and one for the invasion. So i send my cruiser to take out the destroyer meanwhile my transport ignores the destroyer and delivers a tank/guy to Manchuria for a separate battle? Assume victory at sea. Otherwise I assume my transport is dead.
Or is it possible to take over phillipines on turn one as Japan? Cause this is the same mechanic.
Amphibious assaults can be done in two steps, consisting of a sea battle and a land battle. In your example, both the cruiser and the transport would attack the destroyer. If the attackers win, the transport can offload and the land battle will occur. If the transport ends up retreating (or being sunk), the land battle will not occur and the transport may not offload.