From: Georgetown, Texas, USA
There are several general issues with single/multiple sub TFs.
Chance to find the enemy - each TF has a chance, without regard to number of subs in the TF. So 3 TFs with one sub are more likely to encounter the enemy than one TF with three subs.
Which sub attacks - Only one sub from each TF will attack. In a single sub TF there is no option. In a multiple sub TF the "best" sub will be selected. This is based on damage, ammo, (and fuel?) Basically the least damaged with the most ammo. I think fuel is also considered in the spirit of "one more attack before I have to run home to refuel". Once that single sub attacks, the engagement is over. There is no code to support multiple attacks.
Multiple attacks - There is, however, a chance that the same sub TF will re-contact the same enemy TF. If that happens a different sub from a "wolf pack" might be chosen to attack. This could look like coordinated attacks in the combat report but it is really just a series of attacks.
Detection - I do not know is multiple subs increases the chance of detection of the "wolfpack", but I suspect so. I don't think there is special-circumstance code either way, so whatever the general detection code does... In most circumstances, more ships in the the TF means higher chances of detection.
For the record - I never run wolfpacks. I prefer "line" patrol zones - two points fairly close together so the sub bounces back and forth in the targeted area. Multiple sub TFs can be placed in the same area, with patrol lines crossing.