Formation "Support" order directives, would essentially have the formation stay in the same relative position to the formation it is supporting as it moves with it, right? However, would you want to state whether the formation should support a specific flank or rear? There could be a significant latitude in how this directive is interpreted or should be interpreted.
-Yahoo Group, 5/1/16
Frankly, as you say, there is a lot of latitude in how the rule is written. The term used in the text is “shadow”, in convention games, introductory games, etc... when players ask how one Formation should shadow another, my general statement is that the supporting Formation may follow behind or on either flank but must remain behind the front of the supported Formation.
-David