Hello, Allan.
If I might be permitted to post what I know (or think I know)?
In the English Civil War, units changed direction primarily by wheeling on a fixed pivot rather than by modern march-and-turn methods. When a unit wheeled, one flank stood fast and acted as the pivot—if wheeling to the right, the right-hand flank remained in place; if to the left, the left-hand flank did so—while the rest of the formation marched around it. Small wheels of up to roughly forty-five degrees could be carried out with little difficulty but larger wheels increasingly strained cohesion, with turns beyond ninety degrees often risking disorder and delay.
Inclining was used, but only in a limited and practical sense. It did not resemble the later, more formal oblique march (cf Fred's SYW Prussians) but instead functioned as a slight diagonal adjustment to correct alignment or prepare for a proper wheel. Commanders prioritised maintaining formation integrity (for obvious reasons!) over executing elegant manoeuvres, so any significant change of direction would normally be handled by wheeling rather than by extended oblique movement. In my ECW gaming, I use it to micro-manage a unit's position.
Units could also perform an about face, turning to confront a threat from the rear or to reposition. This manoeuvre effectively "clubbed" the formation, reversing left and right, which could have implications for command placement and the arrangement of shot and pike.
While entirely valid on the drill field and in more controlled situations, carrying out an about face under battlefield pressure was risky, particularly when close to the enemy and often led to confusion or disorder. It could, however, be used by shotte to deliver fire to the rear during a withdrawal, though this too was hazardous.
Stepping back was a recognised and useful practice, especially for bodies of shotte. Units could move backwards while maintaining their facing, allowing them to continue firing as they yielded ground, drew the enemy forward, or avoided immediate contact. Pike formations were less flexible but could still retire in an orderly fashion. It was typically carried out at reduced speed and with some risk to cohesion if conducted under pressure.
Overall, movement in this period emphasised steadiness and cohesion over flexibility. More complex manoeuvres—especially near the enemy—carried an inherent risk of disorder which often meant disaster.
As a wargamer, your challenge will be to decide which units of Foot are trained enough to do this flawlessly, which can but slowly & which (untrained) might well foul it all up. In my games, I've found it best to get the Foot in formation & position as soon as possible, so little more than forward movement is needed.If anything "fancy" is needed, use Dragoons or Commanded Shotte units.
Anyway, this will do till someone more knowledgeable wanders by.