what is the proper isolation joint to use in this situation 1

Why isolate the top? Can use cut 'sonotube ring' or better, polyurethane wrap, to provide a gap for installation, and remove it the first time it is lifted. Careful though with sonotube you may have difficulty removing the concrete. One of my first slab on grades (when I was a real know-it-all rookie) I had plywood separation strips, and I was positive the concrete would shrink away and it would be easy to pull out the plywood strips... betcha they are still there...

Dik

That's why I'm asking because I don't really know what to use. I've not used isolation joint for this purpose before (needing to lift the slab).

I only want the slab (2nd pour) not to bond with the drilled pier for easy lifting.

Use asphalt felt (No. 30 felt) or coat the top of pier with asphalt mastic. Both would actually be better. Be sure to coat down the side of the pier past the expected depth of concrete cap. Don't rely on synthetic liquid bond breaker.

I doubt actual "tar" paper is readily available.

Cast the slab separately from the piles, then set it on the piles

Thanks Ron

Motorcity - I was thinking about that but I want the slab to have some more lateral resistance instead of just relying on friction.
The possibility of this slab being lifting after in place is small.