If the Hollister is 1 3/4" (or whatever size you use) and the insert is the same, you should be able to use it. And yes, the inserts were made to use with a flat wafer, to give it a little convexity. Once you get some convexity, you may be able to also use the Eakins, which can give you even more convexity. Good luck, I hope it works for you.
If they don't work, I'm sure Hollister has a pre-cut convex flange/wafer. If your stoma isn't exactly round, order the cut size the size of the longes part of your stoma and use an Eakin tight around the stoma. You should still get a great seal.
49 years old, CD since I was a child.
Six resection surgeries, permanent ostomy, adverse reactions to Remicade, finally off of Prednisone, hoping for a long remission from this last surgery.