In a drawn combat individual models remain where they are if they're touching base-to-base. Otherwise, fighting units from both sides must move all models up to 6" forward, ignoring difficult terrain, into base contact with enemies, or as close as they can where this is not possible. They must move against unengaged models in preference to models already in base contact. If both sides have unengaged models to move in roll a D6 each, highest score moves in first.
Drawn Combats
Source: Core Rulebook 3E, p. 69
In a drawn combat, unengaged models on both sides must move up to 6" into base contact with the enemy, with priority given to models not already engaged.