You will be able to dock with a Shuttle A, but I doubt you will be able to lead the Shuttle A to the ISS. The docking offsets
the CG of both ships, so firing the engines will cause some very wierd things to happen.
Why not send a maintenance team with the DGIII, and then you can get the ship fired up again? You could also send one DGIII
to rescue the crew and then another DGIII to fix the Shuttle A.
Cheers,