Combat against foot and mounted

In a recent game the issue arose of which factors to use in a combat were a pike unit was in contact with enemy foot and enemy mounted.  We settled on using the factors that represented the enemy's main unit.  There wasn't a lot in it (just a single dice).  In our game the enemy foot was the main unit (although they were down to one dice) while the supporting unit (elephants) was able to contribute three dice.  So it was a bit debatable as to who the pike were really fighting :-)

A related issue is that the two enemy units in contact were from different commands.  Therefore I said they couldn't group and so could not provide flank support.  Is that right?

Thanks.

The AAR can be found here: https://onesidedminiaturewargamingdiscourse.blogspot.com/2019/04/alexander-empire-versus-classical.html

Yes, count the main Unit.
While in case of Impetus bonus this can be nullified also by the supporting Unit.

As for Units from other Command they do not give Flank Support but can be involved as Supporting Units so provide half dice in melee. This doesn't prevent them to be activated again that turn if their Command was not yet activated.

Thank you.