Ambush fire vs Beyond call of duty order

Hi Mates,
I need your help to understand if we acted correctly in the last game
Situation: during player A game turn a player B infantry squad gain the extra order for succeeding in BCD test and immediatly received a full speed order toward a safer location
Player A has an Mg team, still on ambush fire from previous turn, able to see the moving squad along his course
The facts: we finally agreed that the Mg team can interrupt the move order trying to spot the enemy squad to open fire and  this will be considered the team's action for the turn at no order cost (player A still had enough orders remaining indeed)
Outcomes: the Mg Team spotted only on the first shot and, on 5 D6 rolled, scored only one kill, the squad passed the morale test and proceed the movement to its safe location
Rationale: the agreement was taken considering the move at the same level of a reserve move order; otherwise, if player B squad had received an open fire order, there would be no chances for ambush fire from player A units

Thank in advance
MT

Ambush fire may interrupt enemy order, reserve move interrupts enemy turn. I think the only exception was ambush fire may not interrupt another ambush fire.
So B could have gotten a fire order and it could have been interrupted by A ambush fire.