Rough-in for bath has a 2in drain for the sink(vented), a 4in pipe in the floor 12in from the wall for the toilet and another 4in line 3ft from the back wall and 7ft from another wall. The 2in pipe has a T going over to the vicinity of the 2nd 4in pipe, down into the floor. #1 is the 2nd 4in line for the shower drain? #2 if so, do I need to move it as it is not located in the center of the shower base? Or do I need to dig up the floor to reposition it. There is a cleanout near all of this but out of the way

All shower drains are piped with a 2" p-trap, I also send my vent from shower out of floor 2" and then reduce to 1.5". Then I pipe that 1.5" pipe into the 2" wet vent from the toilet (usually the lavatory is the vent for the toilet if it is 2"... if it is... this vent must continue 2" all the way to vent stack or vent in attic).

I am not sure what another 4" pipe would be for... I think the other 2" pipe (if goes into floor) may be the vent for shower... but where is the box out in floor..?

PICS would help... but anyway, this is all I can offer for now. Let us know more if possible.