Sorry to keep going on but,
Two Squadrons of Horse are in melee combat(A and B). B Squadron is being supported by allied Squadron C.
The initial combat is a draw and both units are required to fight another bound/round of combat(in the same turn). Squadron C freely moves to reinforce Squadron B but Squadron B is wiped out by some extremely impressive Dice rolling in the second bound/Round by Squadron A.
I totally understand that Squadron C is forced to take a Morale Test as if it had lost the actual combat.
If, instead of reinforcing, Squadron C had remained in a Supporting role, would they be required to take a Morale Test? This is where my main confusion lies.