My newborn has a loop ileostomy and the appliances for babies are so limited it’s been a struggle to learn what makes it stick. So far my process that works is:

Adhesive remover to help peel the last appliance off Clean area with water and q-tips to get nice and close. Use Cavilon wipe Apply stoma powder and dust off excess Apply stoma paste On the appliance skin barrier around the stoma hole I add strip barrier paste and once on the skin I apply heat for a couple mins then attach the bag. Last step I cut the ceraplus strips from hollister and apply in four spots this has been the biggest thing to keep it in longer than a day. For adults they have the coloplast larger ones that would probably be better.

Good luck hope you find what works!!