Afaik subcommanders didn't talk to eachother during missions anyway.. They knew radio could be tracked by the enemy. Heck they did it themselves. Wolfpacks where organized by their commanders from germany.
So all we need is an AI wich dives and fires torps submerged and survaced. And if that is posssible MTB's will be able to fire torps also
For instance get orders to attack at say daybreak or sundown.. and then around that time you will see another explosion from an AI sub spawned nearby with same orders.
P.s. check out the actual effectiveness of wolfpacks
http://www.uboat.net/ops/convoys/convoys.php
I always thought when a convoy was picked up by a wolfpack they would decimate the convoy. But mostly they destroyed only 1 or 2 ships, with some exceptions.