pvc

I have a downspout buried drain pipe that was constructed with 3" PVC having what I would call "slip joints" with a "bell" end of a few inches on each 10-foot section. The pipe is marked PWPipe PVC Sewer Pipe ASTM .... One of the slip joints parted by nearly a foot so I'm moving one of the...

I wish to put a T into a short piece (5 inches) of existing 1/2" pvc that is fixed on both sides by non movables (wall valve and water tank input) . I won't be able to flex the cut ends in the pvc to slip the T into place. Any tricks how I can put in a T in this situation? Thanks.