I'm not familiar with Red Alert 3 scripts, but try this attach update:
<AttachUpdate
id="ModuleTag_Attach"
Range="500"
CloseEnoughRange="20.0"
Teleport="true"
UseGeometry="true"
DetachWhenParentHealed="false"
ScanForNewParentWhenDetached="false"
DetachWhenParentOutOfSlavedRange="false"
InitialAttachDelay="0.0s"
ParentStatus="CAN_ATTACK"
Flags="FIND_BEST_PARENT UNCONTAINED_ONLY SAME_PLAYER_ONLY"
>
<ObjectFilter Rule="NONE" Relationship="ALLIES">
<IncludeThing>*This Object Carrying the Dummy*</IncludeThing>
</ObjectFilter>
</AttachUpdate>
For "ParentStatus" if Can_Attack doesn't suit the needs pick from this list:
Code:
<xs:enumeration value="DESTROYED" />
<xs:enumeration value="CAN_ATTACK" />
<xs:enumeration value="UNDER_CONSTRUCTION" />
<xs:enumeration value="UNSELECTABLE" />
<xs:enumeration value="NO_COLLISIONS" />
<xs:enumeration value="NO_ATTACK" />
<xs:enumeration value="AIRBORNE_TARGET" />
<xs:enumeration value="PARACHUTING" />
<xs:enumeration value="REPULSOR" />
<xs:enumeration value="HIJACKED" />
<xs:enumeration value="AFLAME" />
<xs:enumeration value="BURNED" />
<xs:enumeration value="CANNOT_BE_SOLD" />
<xs:enumeration value="IS_FIRING_WEAPON" />
<xs:enumeration value="IS_BRAKING" />
<xs:enumeration value="STEALTHED" />
<xs:enumeration value="HIDDEN" />
<xs:enumeration value="DETECTED" />
<xs:enumeration value="CAN_STEALTH" />
<xs:enumeration value="SOLD" />
<xs:enumeration value="UNDERGOING_REPAIR" />
<xs:enumeration value="RECONSTRUCTING" />
<xs:enumeration value="IS_ATTACKING" />
<xs:enumeration value="NO_AUTO_ACQUIRE" />
<xs:enumeration value="USING_ABILITY" />
<xs:enumeration value="IS_AIMING_WEAPON" />
<xs:enumeration value="NO_ATTACK_FROM_AI" />
<xs:enumeration value="IGNORING_STEALTH" />
<xs:enumeration value="IS_MELEE_ATTACKING" />
<xs:enumeration value="GUARD_SELECTION" />
<xs:enumeration value="LEASHED_RETURNING" />
<xs:enumeration value="DEATH_1" />
<xs:enumeration value="DEATH_2" />
<xs:enumeration value="DEATH_3" />
<xs:enumeration value="DEATH_4" />
<xs:enumeration value="DEATH_5" />
<xs:enumeration value="CONTESTED" />
<xs:enumeration value="CONTESTING_BUILDING" />
<xs:enumeration value="HORDE_MEMBER" />
<xs:enumeration value="RIDERLESS" />
<xs:enumeration value="RIDER_IS_PILOT" />
<xs:enumeration value="RIDER1" />
<xs:enumeration value="RIDER2" />
<xs:enumeration value="RIDER3" />
<xs:enumeration value="RIDER4" />
<xs:enumeration value="NO_SHADOW" />
<xs:enumeration value="IN_STASIS" />
<xs:enumeration value="OUT_OF_PHASE" />
<xs:enumeration value="NEXT_MOVE_IS_REVERSE" />
<xs:enumeration value="IMMOBILE" />
<xs:enumeration value="FLEE_OFF_MAP" />
<xs:enumeration value="NOT_IN_WORLD" />
<xs:enumeration value="INAUDIBLE" />
<xs:enumeration value="CHANTING" />
<xs:enumeration value="ENRAGED" />
<xs:enumeration value="CREATE_DRAWABLE_WITH_LOW_DETAIL" />
<xs:enumeration value="SINKING" />
<xs:enumeration value="RAMPAGING" />
<xs:enumeration value="INSIDE_GARRISON" />
<xs:enumeration value="DEPLOYED" />
<xs:enumeration value="UNATTACKABLE" />
<xs:enumeration value="ENCLOSED" />
<xs:enumeration value="TEMPORARILY_DEFECTED" />
<xs:enumeration value="TAGGED" />
<xs:enumeration value="DEPLOYING" />
<xs:enumeration value="PRIMARY_MEMBER_PRESENT" />
<xs:enumeration value="PORTER_TAGGED" />
<xs:enumeration value="GRAB_AND_DROP" />
<xs:enumeration value="STAND_GROUND" />
<xs:enumeration value="UNCONTROLLABLY_SCARED" />
<xs:enumeration value="SPECIAL_ABILITY_PACKING_UNPACKING_OR_USING" />
<xs:enumeration value="TIBERIUM_VIBRATING" />
<xs:enumeration value="UPDATING_AI" />
<xs:enumeration value="CLONED" />
<xs:enumeration value="IGNORE_AI_COMMAND" />
<xs:enumeration value="RUNNING_DOWN_FROM_BEHIND" />
<xs:enumeration value="DO_NOT_SCORE" />
<xs:enumeration value="CAN_NOT_WALK_ON" />
<xs:enumeration value="MARCH_OF_DEATH" />
<xs:enumeration value="DO_NOT_PICK_ME" />
<xs:enumeration value="INHERITED_FROM_ALLY_TEAM" />
<xs:enumeration value="SWITCHED_WEAPONS" />
<xs:enumeration value="END_FIRE_STATE" />
<xs:enumeration value="BOOKENDING" />
<xs:enumeration value="ELVISH_EXPRESSLY" />
<xs:enumeration value="INSIDE_CASTLE" />
<xs:enumeration value="BUILD_BEING_CANCELED" />
<xs:enumeration value="PENDING_CONSTRUCTION" />
<xs:enumeration value="PHANTOM_STRUCTURE" />
<xs:enumeration value="IN_FORMATION_TEMPLATE" />
<xs:enumeration value="IS_LEAVING_FACTORY" />
<xs:enumeration value="MOVING_TO_DISMOUNT" />
<xs:enumeration value="NO_HERO_PROPERTIES" />
<xs:enumeration value="CAN_ENTER_ANYTHING" />
<xs:enumeration value="HOLDING_THE_RING" />
<xs:enumeration value="INVISIBLE_DETECTED_BY_FRIEND" />
<xs:enumeration value="INVISIBLE_DETECTED" />
<xs:enumeration value="WORKER_REPAIRING" />
<xs:enumeration value="ATTACHED" />
<xs:enumeration value="WONT_RIDE_WITH_YOU" />
<xs:enumeration value="COMMAND_BUTTON_TOGGLED" />
<xs:enumeration value="OCLMONITOR_COMPLETED_TASK" />
<xs:enumeration value="OCLMONITOR_MONITOR_RELEASED" />
<xs:enumeration value="USER_POWERED_DOWN" />
<xs:enumeration value="GARRISONED" />
<xs:enumeration value="BOOBY_TRAPPED" />
<xs:enumeration value="IS_HIDEOUT" />
<xs:enumeration value="SUICIDE_BOMBER_HAS_TARGET" />
<xs:enumeration value="UNIT_WANTS_TO_REGARRISON" />
<xs:enumeration value="IN_COVER" />
<xs:enumeration value="DONT_CLEAR_FOR_BUILD" />
<xs:enumeration value="MATCH_TARGETS_SPEED" />
<xs:enumeration value="HAS_TIBERIUM_GROWTH_MOD" />
<xs:enumeration value="HAS_TIBERIUM_UPGRADE" />
<xs:enumeration value="STEAL_NEXT_UNIT_TRAPPED"/>
<xs:enumeration value="DOES_CONTAIN_TIBERIUM" />
<xs:enumeration value="IS_BEING_HARVESTED" />
<xs:enumeration value="HAS_TIBERIUM_AMMO" />
<xs:enumeration value="SHIELDBODY_ENABLED"/>
<xs:enumeration value="HEALTH_PERCENT_0"/>
<xs:enumeration value="HEALTH_PERCENT_25"/>
<xs:enumeration value="HEALTH_PERCENT_50"/>
<xs:enumeration value="HEALTH_PERCENT_75"/>
<xs:enumeration value="HEALTH_PERCENT_100"/>
<xs:enumeration value="WEAPON_UPGRADED_01"/>
<xs:enumeration value="WEAPON_UPGRADED_02"/>
<xs:enumeration value="WEAPON_UPGRADED_03"/>
<xs:enumeration value="COMBINED_PARENT"/>
<xs:enumeration value="COMBINED_CHILD"/>
<xs:enumeration value="COMBINED_ATTACHED"/>
<xs:enumeration value="LOADED_FROM_MAP"/>
<xs:enumeration value="ATTACKING_GARRISONED_STRUCTURE"/>
<xs:enumeration value="EXITING_COMBINED"/>
<xs:enumeration value="DELAYED_ENTER_STRUCTURE"/>
<xs:enumeration value="DOCKING"/>
<xs:enumeration value="HARVESTING"/>
<xs:enumeration value="BRIDGE_IMPASSABLE"/>
<xs:enumeration value="POWERED_DOWN_EMP"/>
<xs:enumeration value="FORCE_ATTACKING"/>
<xs:enumeration value="FORCE_ATTACK_MOVING"/>
<xs:enumeration value="SCARED_CIVILIAN_CAR"/>
<xs:enumeration value="USER_PARALYZED"/>
<xs:enumeration value="BOOBY_TRAP_EXPLODE"/>
<xs:enumeration value="IS_ENGAGED"/>
<!-- Keeps Model Condition ENGAGED on while on -->
<xs:enumeration value="CARRYING_FLAG"/>
<xs:enumeration value="IS_MOVING_TO_RALLY_POINT"/>
<xs:enumeration value="CAN_SPOT_FOR_BOMBARD" />
<xs:enumeration value="AIRCRAFT_IGNORE_SAMEPLAYER_HANGAR_RULE" />
<xs:enumeration value="NEXT_MOVE_IS_FORCE_ATTACK_MOVE" />
<xs:enumeration value="SPECIALABILITY_ACTIVE" />
<xs:enumeration value="CAN_STEALTH_FROM_PRODUCER" />
Then most likely the Object carrying the attached object would then need to spawn this dummy object. Hope that helps!