Sturmer, The area you seem to be referring to is the Irish sea and convoy SC 7 was an atlantic convoy from Sydney to Aberdeen although what was left of it could well have headed for Liverpool( Edit: Clyde)

. I think all of the sinkings took place around the area of Rockhall. 20 ships were sunk or damaged.
I might be expecting too much of the game for that convoy to be present and playable. One would think it would be included as it is a significant convoy due to the losses it incurred and the ease with which the U boats managed it, proving to be a harsh lesson that the Royal Navy would eventually learn from.
Would it change the outcome of the convoy if I sank a ship that was scripted to be in a radio message at a later time?