Are you asking if you can insert grommets into the added upholstered fabric? Grommet kits are available at JoAnns. An easier method would to be leave the current grommets in place and add the new fabric to the bottom of the existing panels.

It would be a lot easier to just add to the bottom, like rather said. If you want to add to the top, what kind of heading are you planning? Rings would make it easier to form makeshift pleats or shirring it on the rod would just naturally form pleats of sorts, if there's enough fabric.

Let me see if I understand. You're moving up the rod, and adding this fabric as contrast at the top, and putting grommets on the patterned fabric?
I think it would work, as the weight of the solid panel would encourage it to fall into place. You could also just make a cornice or box valance out of the patterned fabric and mount it on a separate rod above the solid panels leaving them just as they are.

I used outdoor upholstery fabric on grommets to cover the stacked washer/dryer is the bathroom. It looks and hangs okay to me.

Thanks everyone - changed my mind on these and went with something different.