There is one rule of movement that applies throughout the game – the 1" rule. Quite simply, with the exception of units engaged in combat, no unit can end its movement within 1" of an enemy unit.
Often, a unit will have to move within 1" of another unit during its move. This is perfectly acceptable, provided that, at the end of the movement, there is 1" between it and any enemy units. At times, once movement is complete, players may have to nudge units further apart, by the smallest amount possible, to maintain this rule, and this is also perfectly acceptable. Both players should agree upon how best to do this and ensure neither gain any unfair advantage.