Hi Frenz,
I have thought of some more info that might help your friend!
The really big turnaround for me was to get the peg tube properly positioned in stomach. Mine was pointing upwards instead of down into stomach, which of course just refluxed up! I have now taped my tube up under my chest and this seems to keep the inside bit pointing the right way!
Another big help, with the mucous has been the oral rinse - made up of bicarbonate of soda and salt with warm water( little pinch of each in glass). Make weak solution and with the help of a monojet syringe, flush as frequently as poss. This cuts the mucous and desensitizes the mouth. I also use a suction pump, battery powered, to remove excess mucous and it has been a Godsend!
Hope this is of some use, all the best to you and your friend,
Frances.