From 2.2.7 Macro Weapons
Quote:
Allocating Hits:
If an attacking formation scores hits both with normal weapons and weapons with the macro-weapon ability, then the opposing player must allocate and make any saves for the normal hits first, and then allocate and make any saves for the macro-weapon hits. Hits from macro-weapons can only be applied to units that are in a position to be hit by a macro-weapon
From 3.2.1 War Engines
Quote:
If a formation includes both war engines and non-war engine units then an attacker must state whether any attacks he makes on the formation will be directed at the war engines or the other units in the formation. Attacks directed at the war engines can only be allocated against war engines if they hit, while attacks directed at other units may not be allocated to the war engines in the formation.