I am doing a store in a mall that has a 600V 3PH 4W feed to it from the main electrical room. I will be installing a transformer in the store and it will need a ground back to the main ER. The ground will have to go in the conduit that serves the 600V disconnect in the store. This conduit already has a bonding conductor in it.

Here is the question. Do I leave the bond in place and pull my ground wire in as well, or do I pull it out and replace it with the ground conductor and use that to bond the 600V disconnect in the store?

The 2nd option makes more sense to me but I wonder which is the best way and why. The first option would leave two grounded condutors in the conduit not counting the neutral which somehow seems wrong.
If this installation were in armoured cable then I would have a ground and a bond basically in parallel.

Which is best?