A unit is considered a Parent Unit if at least half of its models have this Universal Rule. Parent Units treat all Support Units as Insignificant.
Immediately after a Parent Unit passes a Charge Range roll against a non-fleeing enemy unit in the Charge Phase, before performing the Charge Move, any Support Units within 6" of the Parent Unit may perform a support charge. To do so, the Support Unit Declares a Charge against the same enemy unit. Apply all of the usual rules for charging for this out-of-sequence charge (such as Line of Sight, Front Arc, must roll for Charge Range, max one Wheel, etc.), with the exception that the enemy cannot choose a Charge Reaction other than Hold. For the purpose of Charge Moves, treat this as any other case of Combined Charges. When calculating Combat Scores in the following Melee Phase, combine the Rank Bonus of both the Parent Unit and up to one Support Unit that performed a successful support charge (following all normal restrictions), up to a maximum of +6.