If several units have declared a charge against a single unit, then roll the charge distance of these units at the same time. The charge moves of the charging units must be made as far as possible to equalize the number of models fighting from each charging unit. Remember, however, that your primary goal is always to maximize the number of models fighting – it is acceptable to have more models fighting from one unit than from another, if to do otherwise would reduce the overall number of models fighting.
On occasion, exceptional dice rolls from charging units might mean that more units can complete the charge than can fit in base contact with the target. When this happens, the controlling player of the charging units must nominate which units complete the charge. Those units that cannot complete the charge against the target are counted as having made a failed charge.