Its not BM exactly if I am correct . Since she has a rectum no more the mucus build up just comes to the bottom . Its whitish/ yellowish fluid most likely . Immodium can help with the slower stoma output but wont affect the mucus . I had similar condition. Its perfectly fine . Just tell her to try holding it back as much as she can this will help it thicken as I observed . The more I released it the more I had to keep on doing it. Once the pouch is reconnected to the bottom it will stop very quickly.