There's a product by Hollister, which is a Medical Adhesive Spray, Product #7730. Each time u change your Ostomy Appliance, just spray the Adhesive Spray around the inside of your new Flange. It sticks on really well. Hope that helps.
I'm new to this as of March 25th. Looks like we're about in the same bind. Many trial bags used with flanges, etc. You can understand the drill. So far I'm using a Mio bag with convex wafer with the stoma putty ring along with paste. Finish off with tape around the flange. This bag has now lasted come tonight 7 full days. Longest bag yet vs up to 5 in one day. I've rigged mine so much since my incision is right next to it and open still. The bag has a filter and is still working. Prep skin real good with the preps and only use water to clean outside of the adhesive removers. Stoma powder crusting if needed. I also use those gel caps for solidifying my loose output since it's an ileostomy and flat as well. Use the paste on the bag before placing on the flange. Hope this helps. I've been through the mill as well and it just will get you down at times especially whenever a blowout happens on a fresh bag. Good luck and many blessings....Jennifer